so basicly caterham the best is to go at it old school?add oil cooler for part needing it if necessary ?
0w-40 observations in a 5w-30 recom'd vehicle...
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Like I've said previously "follow your manufacturer's recommendations" is currently only "correct" on BITOG when they say "use 20"...if they say anything else, they are incompetent, old school suspender wearers, haven't the oxen capacity to get 20 to the desert outposts...etc....etc.
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Originally Posted By: CATERHAM
And when 10W-60 and 5W-50 grades in your examples are specified are lighter grades also spec'd? The answer is no.
In older engines, the answer was YES! However in recent years the answer has been no, but that really has nothing to do with this argument. But we'll come back to this point later.....
Quote:
And using your Ford example, does Ford recommend anything heavier than the spec' 5W-20 for the Mustang GT even for track use regardless of how high the oil temp's get? Again the answer is no.
No, instead they cripple the engine if the oil temps get too high. So instead of giving people options, they castrate the engine. Again, that does nothing to prove your point. In fact rather, it works to prove MINE.
Quote:
From an engineering view point there is more than one way to deal with high oil temp's than running heavier oil. In fact that's very much the last thing you want do with all the negatives associated with running heavier oil grades when you are not seeing high oil temp's.
Then why do companies do it? Give me some REAL REASONS why Ferrari, with their expertise, Ford, with theirs, Porsche, with theirs, BMW, with theirs, Mercedes, with theirs, GM, with theirs....etc Continue to recommend heavy oils when they apparently have a myriad of ways of otherwise dealing with the issue? I mean, they leverage factory thermostatically controlled oil coolers, huge sumps....etc, yes STILL require heavier oils. So do you know something the engineers from these companies don't? I mean you DID mention "from an engineering standpoint" which would mean that you've worked at engineering lubrication systems for high power density engines for an OEM and have intimate knowledge of the design process in order to make such statements, correct?
Quote:
My advise to anyone with a late model car, is to take full advantage of all the safety management systems that have been engineered into your car and run the lightest oil specified.
There is no lubrication benefit in using anything heavier.
That's a cop-out. Ford REQUIRES 5w-50 or 5w-20 for the Mustang GT depending on whether you have the track pack or not. By your own admission OEM's don't spec a variety of oils anymore in most cases. Running the lightest oil specified in a BMW that spec's 10w-60 leaves you with.... 10w-60! This is like telling people there's no reason to run 10w-60 in a Veyron that spec's it and then telling them to run what the manual says.... WHICH IS 10w-friggin-60!
Are you honestly arguing that somebody is better served running their base GT, which does NOT have a factory oil cooler, on 5w-20 at the track and just assuming that their engine going thermal and cutting power is a better approach than Ford's own technique of modifying or deleting that safety mechanism and running a heavier lubricant in conjunction with an oil cooler? That sounds a bit ridiculous to me. It sounds like the base GT is geared for people whose vehicles will never see a racetrack. And if, by chance, they do, there are safeties in place to prevent the engine oil from getting too hot and unable to provide adequate protection under those circumstances, and so the engine cuts power so that it doesn't spin a rod bearing or 8.
Guys planning on tracking them, Ford is betting, will opt for the Track Pack version, which comes with a big 'ol honkin' oil cooler and spec's 5w-50. So they can go hog wild and not worry about tossing some bi-metal shells into the pan
If your only argument here was that a heavier lubricant is not optimal much of the time, I'd agree with you. But positing that there is no reason to run a heavier lubricant, which was your initial statement, is ridiculous. If that was the case, OEM's wouldn't do it. But they DO do it, and I'd bet that the OEM's know more about engine design than either of us, which means that one of us is wrong, and since I'm the one siding with the OEM, my money is on that person being you.
And when 10W-60 and 5W-50 grades in your examples are specified are lighter grades also spec'd? The answer is no.
In older engines, the answer was YES! However in recent years the answer has been no, but that really has nothing to do with this argument. But we'll come back to this point later.....
Quote:
And using your Ford example, does Ford recommend anything heavier than the spec' 5W-20 for the Mustang GT even for track use regardless of how high the oil temp's get? Again the answer is no.
No, instead they cripple the engine if the oil temps get too high. So instead of giving people options, they castrate the engine. Again, that does nothing to prove your point. In fact rather, it works to prove MINE.
Quote:
From an engineering view point there is more than one way to deal with high oil temp's than running heavier oil. In fact that's very much the last thing you want do with all the negatives associated with running heavier oil grades when you are not seeing high oil temp's.
Then why do companies do it? Give me some REAL REASONS why Ferrari, with their expertise, Ford, with theirs, Porsche, with theirs, BMW, with theirs, Mercedes, with theirs, GM, with theirs....etc Continue to recommend heavy oils when they apparently have a myriad of ways of otherwise dealing with the issue? I mean, they leverage factory thermostatically controlled oil coolers, huge sumps....etc, yes STILL require heavier oils. So do you know something the engineers from these companies don't? I mean you DID mention "from an engineering standpoint" which would mean that you've worked at engineering lubrication systems for high power density engines for an OEM and have intimate knowledge of the design process in order to make such statements, correct?
Quote:
My advise to anyone with a late model car, is to take full advantage of all the safety management systems that have been engineered into your car and run the lightest oil specified.
There is no lubrication benefit in using anything heavier.
That's a cop-out. Ford REQUIRES 5w-50 or 5w-20 for the Mustang GT depending on whether you have the track pack or not. By your own admission OEM's don't spec a variety of oils anymore in most cases. Running the lightest oil specified in a BMW that spec's 10w-60 leaves you with.... 10w-60! This is like telling people there's no reason to run 10w-60 in a Veyron that spec's it and then telling them to run what the manual says.... WHICH IS 10w-friggin-60!
Are you honestly arguing that somebody is better served running their base GT, which does NOT have a factory oil cooler, on 5w-20 at the track and just assuming that their engine going thermal and cutting power is a better approach than Ford's own technique of modifying or deleting that safety mechanism and running a heavier lubricant in conjunction with an oil cooler? That sounds a bit ridiculous to me. It sounds like the base GT is geared for people whose vehicles will never see a racetrack. And if, by chance, they do, there are safeties in place to prevent the engine oil from getting too hot and unable to provide adequate protection under those circumstances, and so the engine cuts power so that it doesn't spin a rod bearing or 8.
Guys planning on tracking them, Ford is betting, will opt for the Track Pack version, which comes with a big 'ol honkin' oil cooler and spec's 5w-50. So they can go hog wild and not worry about tossing some bi-metal shells into the pan
If your only argument here was that a heavier lubricant is not optimal much of the time, I'd agree with you. But positing that there is no reason to run a heavier lubricant, which was your initial statement, is ridiculous. If that was the case, OEM's wouldn't do it. But they DO do it, and I'd bet that the OEM's know more about engine design than either of us, which means that one of us is wrong, and since I'm the one siding with the OEM, my money is on that person being you.
Originally Posted By: CATERHAM
Whether one can notice the difference running a heavier than necessary oil makes that really shouldn't be the reason to do so.
At the back of many members minds, mostly newbies (and of course the hopeless belt and suspenders thicker is better set) it's a myth that there is greater high temp' protection in running a heavier grade especially if it's mentioned as an option by the manufacturer.
The fact of the matter is, there is no lubrication advantage to running the heavier oil (and if you read carefully what the OEMs recommend they all confirm it) but there are lots of reasons not to.
I guess those ignorant Subaru engineers aren't reading your posts. From my Forester's manual:
"Engine oil viscosity (thickness) affects fuel economy. Oils of lower viscosity provide better fuel economy. However, in hot weather, oil of higher viscosity is required to properly lubricate the engine."
But it's a 2010 model so maybe this is old school thinking?
Whether one can notice the difference running a heavier than necessary oil makes that really shouldn't be the reason to do so.
At the back of many members minds, mostly newbies (and of course the hopeless belt and suspenders thicker is better set) it's a myth that there is greater high temp' protection in running a heavier grade especially if it's mentioned as an option by the manufacturer.
The fact of the matter is, there is no lubrication advantage to running the heavier oil (and if you read carefully what the OEMs recommend they all confirm it) but there are lots of reasons not to.
I guess those ignorant Subaru engineers aren't reading your posts. From my Forester's manual:
"Engine oil viscosity (thickness) affects fuel economy. Oils of lower viscosity provide better fuel economy. However, in hot weather, oil of higher viscosity is required to properly lubricate the engine."
But it's a 2010 model so maybe this is old school thinking?
It's always great when someone who knows very little about engineering freely hands out his or her engineering advice.
is it possible that the oil too thin fall too fast to properly lubricate in certain circumstance?if so maybe an oil thermostat could be nice?or two !
Originally Posted By: yvon_la
that is why I try to understand what zinc and molybdenum have (for oil)that magnesium and calcium don't?
ZDDP is usually an AW compound, moly is usually as a FM, but occasionally AW, and calcium usually a detergent. Of course, they all have other purposes, too, with more than one function. That doesn't mean one or two compounds are ideal at replacing everything else.
that is why I try to understand what zinc and molybdenum have (for oil)that magnesium and calcium don't?
ZDDP is usually an AW compound, moly is usually as a FM, but occasionally AW, and calcium usually a detergent. Of course, they all have other purposes, too, with more than one function. That doesn't mean one or two compounds are ideal at replacing everything else.
Originally Posted By: CATERHAM
The fact of the matter is, there is no lubrication advantage to running the heavier oil (and if you read carefully what the OEMs recommend they all confirm it) but there are lots of reasons not to.
Efficiency...recommended...lubrication advantage.
That's not always the point, you know. More like exploration, personal experience, and because-we-want-to-try-it.
I saw with my own eyes that the UOAs were extremely similar between the oil weights and that it didn't make a whole lot of difference, except for perhaps mpgs or response. At the edge of speed/heat/performance it would be a different animal, but where the bulk of us tread...not much of an issue.
The fact of the matter is, there is no lubrication advantage to running the heavier oil (and if you read carefully what the OEMs recommend they all confirm it) but there are lots of reasons not to.
Efficiency...recommended...lubrication advantage.
That's not always the point, you know. More like exploration, personal experience, and because-we-want-to-try-it.
I saw with my own eyes that the UOAs were extremely similar between the oil weights and that it didn't make a whole lot of difference, except for perhaps mpgs or response. At the edge of speed/heat/performance it would be a different animal, but where the bulk of us tread...not much of an issue.
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Originally Posted By: CATERHAM
My advise to anyone with a late model car, is to take full advantage of all the safety management systems that have been engineered into your car and run the lightest oil specified.
There is no lubrication benefit in using anything heavier.
You do realize that most cars on the road today do not have any such system? Just because you've heard of a handful of cars that do employ a thermal management strategy, you just assume they all have it?
I can tell you from my experience working on many makes and models of cars that most do not even have an oil temp sensor, let alone an oil temperature management system.
It seems you are mixing up cooling system limp home features with lubrication thermal management strategies. GM commercialized the cooling system fail-safe limp home feature back in the 90's, where cylinders are purposefully misfired in order to reduce thermal loading on the engine and enable limited operation with no coolant. They do not however, have any kind of oil temp sensor. Other than some Ford models, there are not many other vehicles that have this type of cooling system fail-safe feature.
In terms of oil temp management, very few vehicles employ such a feature, except where deemed necessary by the manufacturer (some famous late model examples are the Nissan VQ engine in some models, the Ford Mustang, and some German cars - especially AMG / BMW M / Audi RS models).
My advise to anyone with a late model car, is to take full advantage of all the safety management systems that have been engineered into your car and run the lightest oil specified.
There is no lubrication benefit in using anything heavier.
You do realize that most cars on the road today do not have any such system? Just because you've heard of a handful of cars that do employ a thermal management strategy, you just assume they all have it?
I can tell you from my experience working on many makes and models of cars that most do not even have an oil temp sensor, let alone an oil temperature management system.
It seems you are mixing up cooling system limp home features with lubrication thermal management strategies. GM commercialized the cooling system fail-safe limp home feature back in the 90's, where cylinders are purposefully misfired in order to reduce thermal loading on the engine and enable limited operation with no coolant. They do not however, have any kind of oil temp sensor. Other than some Ford models, there are not many other vehicles that have this type of cooling system fail-safe feature.
In terms of oil temp management, very few vehicles employ such a feature, except where deemed necessary by the manufacturer (some famous late model examples are the Nissan VQ engine in some models, the Ford Mustang, and some German cars - especially AMG / BMW M / Audi RS models).
Originally Posted By: Garak
Originally Posted By: FetchFar
I can't get over the use of purple dye in their oil.
Most oils are dyed. What makes purple any less valid a choice?
Purple dye seems mickey-mouse to me. Gimmicky. Marketing goo. I am surprised that some other oils are dyed as well. I know the old German Castrol 0w-30 had a distinct green tinge, then became gold in later versions, Was that dye?
Originally Posted By: FetchFar
I can't get over the use of purple dye in their oil.
Most oils are dyed. What makes purple any less valid a choice?
Purple dye seems mickey-mouse to me. Gimmicky. Marketing goo. I am surprised that some other oils are dyed as well. I know the old German Castrol 0w-30 had a distinct green tinge, then became gold in later versions, Was that dye?
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Originally Posted By: FetchFar
Originally Posted By: Garak
Originally Posted By: FetchFar
I can't get over the use of purple dye in their oil.
Most oils are dyed. What makes purple any less valid a choice?
Purple dye seems mickey-mouse to me. Gimmicky. Marketing goo. I am surprised that some other oils are dyed as well. I know the old German Castrol 0w-30 had a distinct green tinge, then became gold in later versions, Was that dye?
Royal Purple was mainly used in the beginning for industrial use, pumps, machinery etc. The purple dye was to help determine whose oil was in the machinery.
I use Royal Purple,and can say the purple dye color burns off fast.The oil is amber colored after a few miles.
Originally Posted By: Garak
Originally Posted By: FetchFar
I can't get over the use of purple dye in their oil.
Most oils are dyed. What makes purple any less valid a choice?
Purple dye seems mickey-mouse to me. Gimmicky. Marketing goo. I am surprised that some other oils are dyed as well. I know the old German Castrol 0w-30 had a distinct green tinge, then became gold in later versions, Was that dye?
Royal Purple was mainly used in the beginning for industrial use, pumps, machinery etc. The purple dye was to help determine whose oil was in the machinery.
I use Royal Purple,and can say the purple dye color burns off fast.The oil is amber colored after a few miles.
Originally Posted By: FetchFar
Originally Posted By: Garak
Originally Posted By: FetchFar
I can't get over the use of purple dye in their oil.
Most oils are dyed. What makes purple any less valid a choice?
Purple dye seems mickey-mouse to me. Gimmicky. Marketing goo. I am surprised that some other oils are dyed as well. I know the old German Castrol 0w-30 had a distinct green tinge, then became gold in later versions, Was that dye?
Huh.
Motul dyes their oil too a green colour. One of the highest quality lubricants available dyes their oil,as does valvoline with premium blue and a handful of others,but the fact that's the lubricant is coloured in some way affects the quality of the product making it sub-standard in some way.
What nonsense.
As far as thicker grades in performance vehicles I certainly see and understand caterhams point however I'm leaning the other way here.
Yes an engine oils additive package is formulated to lower wear,but film thickness has to be important too,isn't it.
And even though I'm sure 5w-20 is still doing its job at 265f I'm a whole lot more comfortable using a 0w-40 when my oil temps get that hot than the 5w-20 specified for my hemi.
Now in the winter and when my oil temps never break 225f I've got 5w-20 in my hemi. I see absolutely no point in going thicker because oil temps aren't elevated and the engine is operating within it's designed range,but in the summer when I'm driving the car hard,and oil temps skyrocket I don't feel comfortable with a 5w-20,even though the oil just might be fine,the slightly thicker oil film at that temp I get with a 40 grade means I'm not thinking about whether the engine and oil is ok,I'm mashing the pedal down,and smiling.
Now my c3 for example. I'm going to end up using a 5w-20 in it in the winter,because it's not going to be towing the camper and family up the mountains at radium,the truck will be driving my girl to and from work and shuttling the boy to hockey.
In the summer the engine will be taxed much more and oil temps are going to get elevated,and I'm much more comfortable with a 30 or 40 grade under those operating conditions.
Does it need slightly thicker oil,probably not,but it does have 200k,it will be worked hard and the pennies extra in fuel consumed at start up aren't a factor in a vehicle that gets 17mpg anyways.
In my girls windstar I use 5w-20. She doesn't tow. It's not operated at its max load,it's a hauler driving the kids to wherever and operated well within it's designed limits and doesn't consume any oil,so I see no need to go up a grade.
These blanket oil recommendations make no sense to me. I feel that engines aren't all operated in the same conditions by the same operators and the grade should be matched to the conditions,not one size fits all.
Originally Posted By: Garak
Originally Posted By: FetchFar
I can't get over the use of purple dye in their oil.
Most oils are dyed. What makes purple any less valid a choice?
Purple dye seems mickey-mouse to me. Gimmicky. Marketing goo. I am surprised that some other oils are dyed as well. I know the old German Castrol 0w-30 had a distinct green tinge, then became gold in later versions, Was that dye?
Huh.
Motul dyes their oil too a green colour. One of the highest quality lubricants available dyes their oil,as does valvoline with premium blue and a handful of others,but the fact that's the lubricant is coloured in some way affects the quality of the product making it sub-standard in some way.
What nonsense.
As far as thicker grades in performance vehicles I certainly see and understand caterhams point however I'm leaning the other way here.
Yes an engine oils additive package is formulated to lower wear,but film thickness has to be important too,isn't it.
And even though I'm sure 5w-20 is still doing its job at 265f I'm a whole lot more comfortable using a 0w-40 when my oil temps get that hot than the 5w-20 specified for my hemi.
Now in the winter and when my oil temps never break 225f I've got 5w-20 in my hemi. I see absolutely no point in going thicker because oil temps aren't elevated and the engine is operating within it's designed range,but in the summer when I'm driving the car hard,and oil temps skyrocket I don't feel comfortable with a 5w-20,even though the oil just might be fine,the slightly thicker oil film at that temp I get with a 40 grade means I'm not thinking about whether the engine and oil is ok,I'm mashing the pedal down,and smiling.
Now my c3 for example. I'm going to end up using a 5w-20 in it in the winter,because it's not going to be towing the camper and family up the mountains at radium,the truck will be driving my girl to and from work and shuttling the boy to hockey.
In the summer the engine will be taxed much more and oil temps are going to get elevated,and I'm much more comfortable with a 30 or 40 grade under those operating conditions.
Does it need slightly thicker oil,probably not,but it does have 200k,it will be worked hard and the pennies extra in fuel consumed at start up aren't a factor in a vehicle that gets 17mpg anyways.
In my girls windstar I use 5w-20. She doesn't tow. It's not operated at its max load,it's a hauler driving the kids to wherever and operated well within it's designed limits and doesn't consume any oil,so I see no need to go up a grade.
These blanket oil recommendations make no sense to me. I feel that engines aren't all operated in the same conditions by the same operators and the grade should be matched to the conditions,not one size fits all.
Originally Posted By: FetchFar
Purple dye seems mickey-mouse to me. Gimmicky. Marketing goo. I am surprised that some other oils are dyed as well. I know the old German Castrol 0w-30 had a distinct green tinge, then became gold in later versions, Was that dye?
As far as I know, that was dye, too. To further expand on RazorsEdge's point about Royal Purple industrial lubes, take a read through RP's industrial catalog. It's the only one I've seen that even comes close to rivaling XOM's, and in some cases even has more convenient package sizes.
Purple dye seems mickey-mouse to me. Gimmicky. Marketing goo. I am surprised that some other oils are dyed as well. I know the old German Castrol 0w-30 had a distinct green tinge, then became gold in later versions, Was that dye?
As far as I know, that was dye, too. To further expand on RazorsEdge's point about Royal Purple industrial lubes, take a read through RP's industrial catalog. It's the only one I've seen that even comes close to rivaling XOM's, and in some cases even has more convenient package sizes.
Duckhams 15W-50 mineral was green in the mid 80s (that's the one that I used to mix with M1 15W-50).
As to dyes, Castrol has gone one better
http://www.bobistheoilguy.com/forums/ubbthreads.php/topics/3245514/Castrol_Edge_Professional_-_Bl
As to dyes, Castrol has gone one better
http://www.bobistheoilguy.com/forums/ubbthreads.php/topics/3245514/Castrol_Edge_Professional_-_Bl
Concerning dyes in oil, I know Quaker State recently (not now) used clear quart bottles, kind of 'cool' I guess, and they always looked amber, not really interesing. I mean, who walked up to it in the store and bought it because of its hipster amber color? Color is mostly a distraction for motor oil. (Other fluids already have distinct colors for leak ID, so no need for engine oil.) I guess if it helps marketing & doesn't hurt anything, then go ahead and increase the cost of production by a penny a quart to dye it. Why not....
Originally Posted By: Shannow
As to dyes, Castrol has gone one better
Maybe I should run an OCI of that and do the drain under black light.
As to dyes, Castrol has gone one better
Maybe I should run an OCI of that and do the drain under black light.
Using a 40 in an engine that has 30 recommended, one would have to know where on the Stribeck Curve in the journal bearings we are for the conditions of sustained max torque at a low rpm (aka lugging) which might occur when pulling a load up a mild hill for a while. ...... Since a 20 weight is close to a 30 anyway, its viscosity is 'only' about 20% different, and then maybe another 20% difference in going from a 30 to a 40 weight again. So, maybe a 40% difference in hot viscosity from a 20 to a 40 weight oil. ..... Relate a that to the Stribeck Curve, at which an engineer designs the journal bearing to run a 0.8 (assumed, seems to be a good design target), speced for a 30 oil, so we get a Stribeck of about 1.1 if we use a 40 oil (not much change really), and if we use a 20 weight oil the Stribeck goes down to around 0.5, still well above the minimum oil film thickness (MOFT) at Stribeck 0.1
http://www.stle.org/resources/lubelearn/lubrication/ for a Stribeck Curve to stare at.
Conclusion: No big deal in going from a 30 to a 40 weight, and you can even go to a 20 weight and still stay above the MOFT for the journal bearings at the worst case lugging conditions the engineers design the journal bearings for (area, speed, viscosity, load).
http://www.stle.org/resources/lubelearn/lubrication/ for a Stribeck Curve to stare at.
Conclusion: No big deal in going from a 30 to a 40 weight, and you can even go to a 20 weight and still stay above the MOFT for the journal bearings at the worst case lugging conditions the engineers design the journal bearings for (area, speed, viscosity, load).
Originally Posted By: FetchFar
Using a 40 in an engine that has 30 recommended, one would have to know where on the Stribeck Curve in the journal bearings we are for the conditions of sustained max torque at a low rpm (aka lugging) which might occur when pulling a load up a mild hill for a while. ...... Since a 20 weight is close to a 30 anyway, its viscosity is 'only' about 20% different, and then maybe another 20% difference in going from a 30 to a 40 weight again. So, maybe a 40% difference in hot viscosity from a 20 to a 40 weight oil. ..... Relate a that to the Stribeck Curve, at which an engineer designs the journal bearing to run a 0.8 (assumed, seems to be a good design target), speced for a 30 oil, so we get a Stribeck of about 1.1 if we use a 40 oil (not much change really), and if we use a 20 weight oil the Stribeck goes down to around 0.5, still well above the minimum oil film thickness (MOFT) at Stribeck 0.1
http://www.stle.org/resources/lubelearn/lubrication/ for a Stribeck Curve to stare at.
Conclusion: No big deal in going from a 30 to a 40 weight, and you can even go to a 20 weight and still stay above the MOFT for the journal bearings at the worst case lugging conditions the engineers design the journal bearings for (area, speed, viscosity, load).
I think this is part of the point caterham is trying to make,more or less.
And for the most part I understand the point however unless I see with my own eyes upon tear down that elevated oil temps,50f above normal cruising temp or more,doesn't increase engine wear or longevity I think I'm just gonna stick with my plan to match oil grade to the operating conditions.
I mean for example all my work vans get the on sale oil in the appropriate grades,and aren't driven anywhere near what I'd call hard or extreme. They do experience long idle times but are driven lightly and below the speed limit for the most part,and achieve astronomical mileages tells me I'm doing something right.
I just success by how much I spend in repairs.
If I spend a few extra bucks maintaining vehicles but they never require repairs brought on by neglect then I call that a successful maintenance plan.
Using a 40 in an engine that has 30 recommended, one would have to know where on the Stribeck Curve in the journal bearings we are for the conditions of sustained max torque at a low rpm (aka lugging) which might occur when pulling a load up a mild hill for a while. ...... Since a 20 weight is close to a 30 anyway, its viscosity is 'only' about 20% different, and then maybe another 20% difference in going from a 30 to a 40 weight again. So, maybe a 40% difference in hot viscosity from a 20 to a 40 weight oil. ..... Relate a that to the Stribeck Curve, at which an engineer designs the journal bearing to run a 0.8 (assumed, seems to be a good design target), speced for a 30 oil, so we get a Stribeck of about 1.1 if we use a 40 oil (not much change really), and if we use a 20 weight oil the Stribeck goes down to around 0.5, still well above the minimum oil film thickness (MOFT) at Stribeck 0.1
http://www.stle.org/resources/lubelearn/lubrication/ for a Stribeck Curve to stare at.
Conclusion: No big deal in going from a 30 to a 40 weight, and you can even go to a 20 weight and still stay above the MOFT for the journal bearings at the worst case lugging conditions the engineers design the journal bearings for (area, speed, viscosity, load).
I think this is part of the point caterham is trying to make,more or less.
And for the most part I understand the point however unless I see with my own eyes upon tear down that elevated oil temps,50f above normal cruising temp or more,doesn't increase engine wear or longevity I think I'm just gonna stick with my plan to match oil grade to the operating conditions.
I mean for example all my work vans get the on sale oil in the appropriate grades,and aren't driven anywhere near what I'd call hard or extreme. They do experience long idle times but are driven lightly and below the speed limit for the most part,and achieve astronomical mileages tells me I'm doing something right.
I just success by how much I spend in repairs.
If I spend a few extra bucks maintaining vehicles but they never require repairs brought on by neglect then I call that a successful maintenance plan.
My last post can be summarized to say: It appears that in using a 20 vs. 30 vs. 40 oil, in a car speced to a 30 weight, we stay on the lower flat portion of the Stribeck Curve in the crank bearings. And using a 20 oil is still a 5-times margin on the Stribeck. ... So, no big controversy.
side note: engineers can just increase crank bearing surface area by a mere 20% to account for difference between a 20 weight and 30 oil if they wanted to.
side note: engineers can just increase crank bearing surface area by a mere 20% to account for difference between a 20 weight and 30 oil if they wanted to.
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