Noak and wear

[FetchFar]

Originally Posted By: fdcg27
Umm, no piston squirters aren't used for lubrication.
They're used for piston cooling, mainly in turbocharged engines.
T.......


My non-turbo car has oil jets, and they do play a role in wall lubrication as well as cooling. Granted most of the cylinder wall lube comes from crankshaft spray, so you are mostly correct. Remember the original point is that NOT all is pressure-fed. Now notice what happens when thicker cold oil tries to make it up to the cylinder wall by being flung off the crank, it doesn't get there as easily as thinner oil.

 

[OVERKILL]

Originally Posted By: FetchFar
Wrong, remember piston squirters for cylinder walls/rings, on modern car engines? Needs thinner oil to coat walls.


Most engines lubricate the piston/ring/wall interface through spray that comes across the bearing and out the crank/rod interface. Usually there is a slit in either the crank or rod (sometimes both) that creates a (pressurized) fan-like pattern of oil spray. And while an oil of sub-optimal viscosity (due to start-up temperature) may not spray in an ideal fashion, it is the job of the AW additives to prevent wear in this area until the oil is thin enough to coat the walls correctly. This is helped by the fact that the piston (and walls) are some of the fastest heating parts of the engine, bested only by the valves and exhaust manifold(s).

Note that a significant player in determining wear in this area is engine design itself. Ford's old 302HO Windsor engine stands out as historically being an engine that, regardless of lubricant choice, showed next to no bore or piston wear even at extremely high mileage. It isn't uncommon to tear-down an old 5.0L and see pristine bores with visible cross-hatching and almost perfect pistons. This is due to the relatively tall piston and short stroke (3") that resulted in very little rock and scrub. I've seen these engines apart running anything from 5w30 to 20w-50 and the bores and pistons looked immaculate. The only problem I've seen has been varnish/coking in the ring lands from engines run on poor quality lubricants. Those run on a quality lubricant of any viscosity didn't exhibit that problem.

Quote:
Also, the valve stems are not pressure fed,


No, but usually what delivers oil to the valve stems is. On a pushrod engine, that would be the pushrod, which then forces oil out through the orifice in the top of the rocker under pressure, where it runs down and oils the springs and valves. This oil's purpose is also to cool the springs of course, as they generate substantial heat. The process is similar for a roller rocker, except the flow pattern is a little different and they sometimes have a smaller orifice.

Regardless of the type of rocker used, oil delivery is next to immediate on start-up unless the oil filter is empty. And the quantity of oil observed is substantial.

Quote:
neither are the roller bearings in the valvetrain. ...


Which roller bearings? Are you referring to a roller-fulcrum rocker? Needle bearings in a roller lifter? Both are lubricated directly from areas of pressure.

Quote:
Also, positive displacement pumps turn over slower when cold starting a thicker oil.


The pump turns the same speed regardless of what is in the pan, because its speed is directly bound to either the speed of the crank or the speed of the cam. So if an engine takes two rotations to fire, that pump displaces the same amount of oil if it is 0w-20 or 20w-50. That's not to say that one should have 20w-50 in the pan when it is -30C, as that can overrun the relief on the pump and cause excessive system pressure resulting in a burst filter, collapsed media, blown filter seal or, in extreme cold, the oil may not even pump.

Now if you meant to say that the ENGINE may turn over slower when cold starting with a thicker oil, that's certainly a possibility. But that will also depend on starter, engine, battery size....etc. My M5 turned over faster this past winter with 5w-40 in it than our Expedition did with 0w30 in it because it had a newer battery for example.

 

[turtlevette]

I'm starting to think a thin oil with an excellent base stock and excellent wear additive is the best of both worlds. Gets everywhere it needs to right away and still wear protects when film breaks down, yet still has an impressive film strength for a thin oil.

And I still don't buy the assertion that the thickness of oil is directly related to film strength. A thin oil of superior molecular composition could easily have a much better film strength than a thick mineral oil.

I'm going to eventually switch over to the RP 0W-20 with the synerlec on the vette, TA and stang. I would bet anyone here it will wear protect better than any 0W-40 euro oil.

 

[FetchFar]

overkill, not a bad discussion. It confirms what I've been saying about the fact: Some important areas are not directly pressure fed. They rely on flinging or seeping into tiny areas. My GM 3.6L 2011 V6 oil jets help lube cylinder walls, and it also uses splashing from the crank, with some from the wrist pin (not sure about wrist pin to wall). .... Back to the main point: Cold thick oil doesn't fling/seep well, meaning rings and other parts are left hung out to dry for a while cold, and lower visc oils help reduce that problem.

 

[FetchFar]

Originally Posted By: turtlevette
I'm starting to think a thin oil with an excellent base stock and excellent wear additive is the best of both worlds. Gets everywhere it needs to right away and still wear protects when film breaks down, yet still has an impressive film strength for a thin oil.

And I still don't buy the assertion that the thickness of oil is directly related to film strength. A thin oil of superior molecular composition could easily have a much better film strength than a thick mineral oil.

I'm going to eventually switch over to the RP 0W-20 with the synerlec on the vette, TA and stang. I would bet anyone here it will wear protect better than any 0W-40 euro oil.


I've always thought Redline's polyol esters had greater film strength. Still, pao and other group III's seem to be very good as well, so I've gone with PAO/groupIII instead for the complete engineering package offered by SOPUS, etc. ... Certainly the Euro-spec oils place a lot of emphasis on HTHS for crank bearing performance, which 0w-20 oils lack. ... If start-up wear is dominant in your application, then thinner oils are better, and if you have some very cold starts, then thinner is in.

 

[Shannow]

You two need to understand that there's a difference between film strength (nearly an EP concept), and the thickness of the hydrodynamic lubricant between lubricated surfaces.

The latter is purely viscosity driven for a given geometry...the former doesn't matter when the latter is present.

 

[FetchFar]

Originally Posted By: OVERKILL
Which roller bearings? Are you referring to a roller-fulcrum rocker? Needle bearings in a roller lifter? Both are lubricated directly from areas of pressure.


See http://www.supermotors.net/registry/media/167729_1
for an example of the roller rocker bearings getting "splash", drip, squirted oil, NOT pressurized oil. Now put a thick cold oil on that, and the rocker bearings, valve stems, etc. must get the oil to seep in.

 

[OVERKILL]

Originally Posted By: FetchFar
overkill, not a bad discussion. It confirms what I've been saying about the fact: Some important areas are not directly pressure fed. They rely on flinging or seeping into tiny areas. My GM 3.6L 2011 V6 oil jets help lube cylinder walls, and it also uses splashing from the crank, with some from the wrist pin (not sure about wrist pin to wall). .... Back to the main point: Cold thick oil doesn't fling/seep well, meaning rings and other parts are left hung out to dry for a while cold, and lower visc oils help reduce that problem.


While true that some areas are not directly pressure fed, we must put some perspective on some of this. A 0w-40 is going to flow better to all of those areas than a 5w30 or even 5w-20 when things get REALLY cold. And at some point, the difference between the grades isn't all that significant. IE, if oil A is 20,000cP on start-up and oil B is 30,000cP (think -30C start) then is the difference of 10cSt at operating temp between two oils of different grades significant in terms of what is being discussed here? That's the entire purpose behind these wide-split multi-visc oils like 0w-40, 5w-50...etc. To give reasonable cold temp performance while still providing enough high heat protection for high performance applications.

So, given your GM example, the E39 M5, depending on whether it was built before or after March of 2000 spec'd either 10w-60 or 5w30. The engine is physically identical except for a piston ring change. The engine has piston cooling jets and they call for those viscosities whether they are operated in the arctic circle or Texas. BMW seems to not put a whole heck of a lot of emphasis on the significance of viscosity when related to engine life. And many of the ultra high performance cars, ones that will see elevated oil temperatures, spec oils that are, by the metric of many here, incredibly thick. In those circles 10w-60 is a very common grade.

I don't think it is a black and white topic. And I think oils with relatively high VI's and solid CCS/MRV performance like many of the modern 0w-xx Euro grades that we see currently being used are an attempt of having your cake and eating it too. Meeting the >=3.5cP HTHS specs that many of the OEM's require for extended high speed driving, whilst also being able to flow when it is -40C (as the 0w-xx designation demands). And on top of that, being able to satisfy the Long Life requirements that many of the Euro marques also require on top of that!

 

[OVERKILL]

Originally Posted By: FetchFar
Originally Posted By: OVERKILL
Which roller bearings? Are you referring to a roller-fulcrum rocker? Needle bearings in a roller lifter? Both are lubricated directly from areas of pressure.


See http://www.supermotors.net/registry/media/167729_1
for an example of the roller rocker bearings getting "splash", drip, squirted oil, NOT pressurized oil. Now put a thick cold oil on that, and the rocker bearings, valve stems, etc. must get the oil to seep in.


The Modular I'm a bit familiar with

The design is a pressured HLA with a roller camshaft follower. The roller/lobe is lubricated (as shown in the diagram) by oil forced through the HLA under pressure. The cam journals, which ride directly on the machined surface of the head, are also pressure lubed.

 

[OVERKILL]

Originally Posted By: turtlevette
I'm starting to think a thin oil with an excellent base stock and excellent wear additive is the best of both worlds. Gets everywhere it needs to right away and still wear protects when film breaks down, yet still has an impressive film strength for a thin oil.

And I still don't buy the assertion that the thickness of oil is directly related to film strength. A thin oil of superior molecular composition could easily have a much better film strength than a thick mineral oil.


That's the theory, but I don't believe in practice that's the case. That's why NASCAR cars qualify with a thin oil and then run a heavy oil on race day

Quote:
I'm going to eventually switch over to the RP 0W-20 with the synerlec on the vette, TA and stang. I would bet anyone here it will wear protect better than any 0W-40 euro oil.


That's the thing with the Euro oils, tying into your previous statement, they aren't mineral, they are all synthetic in the first place. And if a 0w-20 would protect better, Bugatti would have used it in the Veyron instead of 10w-60. Porsche would be using it in their LeMans program instead of 0w-40....etc. There are plenty of real world examples of heavier oils being used on purpose in situations where, if they could get away with running a thinner oil, they would. Money is not an object in these venues.

That said, if the viscosity requirements of your applications do not exceed the available reserve of the 0w-20 lubricant, you will not see any appreciable benefit from running something heavier than that. Viscosity is of course temperature dependant, so whether your application drives insanely high oil temps or not is a significant factor. Then, as noted many times by Shannow, bearing design comes into play, as do a myriad of other factors.

You won't know unless you try, or if you had intimate design knowledge of the engine family you intend on performing your experiment with. Too thick, you might lose a few HP. But too thin, you can wipe a rod bearing, as I'm sure you are aware. Either way, I'm quite interested to see your experiment! Do you plan on tracking the cars? Do you do that currently?

 

[demarpaint]

Originally Posted By: OVERKILL
Originally Posted By: turtlevette
I'm starting to think a thin oil with an excellent base stock and excellent wear additive is the best of both worlds. Gets everywhere it needs to right away and still wear protects when film breaks down, yet still has an impressive film strength for a thin oil.

And I still don't buy the assertion that the thickness of oil is directly related to film strength. A thin oil of superior molecular composition could easily have a much better film strength than a thick mineral oil.


That's the theory, but I don't believe in practice that's the case. That's why NASCAR cars qualify with a thin oil and then run a heavy oil on race day

Quote:
I'm going to eventually switch over to the RP 0W-20 with the synerlec on the vette, TA and stang. I would bet anyone here it will wear protect better than any 0W-40 euro oil.


That's the thing with the Euro oils, tying into your previous statement, they aren't mineral, they are all synthetic in the first place. And if a 0w-20 would protect better, Bugatti would have used it in the Veyron instead of 10w-60. Porsche would be using it in their LeMans program instead of 0w-40....etc. There are plenty of real world examples of heavier oils being used on purpose in situations where, if they could get away with running a thinner oil, they would. Money is not an object in these venues.

That said, if the viscosity requirements of your applications do not exceed the available reserve of the 0w-20 lubricant, you will not see any appreciable benefit from running something heavier than that. Viscosity is of course temperature dependant, so whether your application drives insanely high oil temps or not is a significant factor. Then, as noted many times by Shannow, bearing design comes into play, as do a myriad of other factors.

You won't know unless you try, or if you had intimate design knowledge of the engine family you intend on performing your experiment with. Too thick, you might lose a few HP. But too thin, you can wipe a rod bearing, as I'm sure you are aware. Either way, I'm quite interested to see your experiment! Do you plan on tracking the cars? Do you do that currently?


Well written, you brought up some great points.

 

[Garak]

Originally Posted By: BlindBaby
I have read that Mobil 1 seems to give a little ground to its peers in the engine wear category, so when looking at UOAs what number determines if the engine wear is low or high and why does Mobil 1 perform in this manner?

Comparing numbers from oil 1 to oil 2 in UOAs to see a difference in wear protection is not a valid use of UOAs.

 

[turtlevette]

Originally Posted By: OVERKILL
Do you plan on tracking the cars? Do you do that currently?


I've been running the vette for many years in a club. Sessions are limited to around 20 minutes with a minimum of a 1 hour cool down time, so about the time the oil starts getting really hot, you shut it down.

The exception was at Mosport once when they had open track and I went thru a whole tank of gas without pitting.

In, the NASCAR example you spoke of I'd be curious of the oils being used for qual and race. Is the light oil 0W-5 and the "heavy" 0W-20 or 30?

I used to have the same philosophy as you but I think it's a new day.

 

[OVERKILL]

I think it varies by event but I believe the light oils are 10's or in that range whilst the heavy oils are 30+ depending on the venue.

When do you think you are going to start your experiment?

 

[FetchFar]

turtlevette, According to Kendall, their 5w-20 synthetic blend (part synthetic) works well in Ford V8s for 100,000 miles using ten thousand mile OCIs in NY taxis. Some more evidence for lighter oils: http://www.phillips66lubricants.com/brands-products/kendall_brand/titanium.aspx#/Videos/taxiTough

 

[turtlevette]

Originally Posted By: OVERKILL
I think it varies by event but I believe the light oils are 10's or in that range whilst the heavy oils are 30+ depending on the venue.

When do you think you are going to start your experiment?


I don't see it as an experiment. I'm changing all my vehicles over to 20wt oil. I really doubt I risk anything using $15 per quart oil.

 

[OVERKILL]

Originally Posted By: FetchFar
turtlevette, According to Kendall, their 5w-20 synthetic blend (part synthetic) works well in Ford V8s for 100,000 miles using ten thousand mile OCIs in NY taxis. Some more evidence for lighter oils: http://www.phillips66lubricants.com/brands-products/kendall_brand/titanium.aspx#/Videos/taxiTough


Yup, most of the modular family, one designed around thinner lubricants, spec's a 20-weight oil and will run nary forever on it.

There are of course exceptions in the higher power density applications like the BOSS 302, Mustang GT Track Pack, Ford GT and the Shelby cars, all of which spec 5w-50, but for the most part, 5w-20 is the called for viscosity and has been proven to work extremely well under basically all operating conditions you are likely to encounter and all usage profiles. Ford has done a good job in controlling oil temperature through sump size, the fitment of coolers where necessary and specific output, which of course works to heat the oil.

 

[OVERKILL]

Originally Posted By: turtlevette
Originally Posted By: OVERKILL
I think it varies by event but I believe the light oils are 10's or in that range whilst the heavy oils are 30+ depending on the venue.

When do you think you are going to start your experiment?


I don't see it as an experiment. I'm changing all my vehicles over to 20wt oil. I really doubt I risk anything using $15 per quart oil.



Not an experiment with the Mustang (which probably spec's a 5w-20 anyway) but with the GM engine, you are certainly going thinner than spec'd, so I would still call that an experiment, even if you've already got a pretty good idea of the outcome

 

[Shannow]

Originally Posted By: FetchFar
Anyway, I did read an SAE paper a few years ago which mentioned how 20 oils lubricated the rings better,


Does cylinder wear count as lubrication ?

 

[il_signore97]

Originally Posted By: OVERKILL
Originally Posted By: FetchFar
overkill, not a bad discussion. It confirms what I've been saying about the fact: Some important areas are not directly pressure fed. They rely on flinging or seeping into tiny areas. My GM 3.6L 2011 V6 oil jets help lube cylinder walls, and it also uses splashing from the crank, with some from the wrist pin (not sure about wrist pin to wall). .... Back to the main point: Cold thick oil doesn't fling/seep well, meaning rings and other parts are left hung out to dry for a while cold, and lower visc oils help reduce that problem.


While true that some areas are not directly pressure fed, we must put some perspective on some of this. A 0w-40 is going to flow better to all of those areas than a 5w30 or even 5w-20 when things get REALLY cold. And at some point, the difference between the grades isn't all that significant. IE, if oil A is 20,000cP on start-up and oil B is 30,000cP (think -30C start) then is the difference of 10cSt at operating temp between two oils of different grades significant in terms of what is being discussed here? That's the entire purpose behind these wide-split multi-visc oils like 0w-40, 5w-50...etc. To give reasonable cold temp performance while still providing enough high heat protection for high performance applications.

So, given your GM example, the E39 M5, depending on whether it was built before or after March of 2000 spec'd either 10w-60 or 5w30. The engine is physically identical except for a piston ring change. The engine has piston cooling jets and they call for those viscosities whether they are operated in the arctic circle or Texas. BMW seems to not put a whole heck of a lot of emphasis on the significance of viscosity when related to engine life. And many of the ultra high performance cars, ones that will see elevated oil temperatures, spec oils that are, by the metric of many here, incredibly thick. In those circles 10w-60 is a very common grade.

I don't think it is a black and white topic. And I think oils with relatively high VI's and solid CCS/MRV performance like many of the modern 0w-xx Euro grades that we see currently being used are an attempt of having your cake and eating it too. Meeting the >=3.5cP HTHS specs that many of the OEM's require for extended high speed driving, whilst also being able to flow when it is -40C (as the 0w-xx designation demands). And on top of that, being able to satisfy the Long Life requirements that many of the Euro marques also require on top of that!



Great discussion. Just to add to Overkill's and Shannow's posts about lubricant viscosity itself, we also have to remember that engine wear on a cold start is not always lubricant related at all. There were SAE studies done that showed a high percentage of the wear that actually does occur at start up has a lot to do with acid formation in the combustion chamber during the (short) warm up period, and not due to cold oil. The resulting wear was mostly attributed to chemical / corrosive wear and not mechanical. Also, there are other factors such as sub-optimal piston / ring / bore clearances during warm up, etc. Oiled areas within an engine will get lubricated with any reasonable and appropriate grade of oil used for the given ambient temperatures expected.

Also, I recall another SAE study (or could have been the same one as above) where 4 tests were done to quantify wear in different engine operating conditions. One was cold oil, cold engine. Second was hot oil, cold engine. Third was cold oil, hot engine. Last was hot oil, hot engine. The wear rates mostly correlated to engine temperature, not oil temperature. This was done with a GM 3.8L engine I think. I don't have an SAE subscription any longer, so I can't access the documents to double check.

And FarFetch, regarding piston spray jets, they actually operate mostly on the basis of oil pressure, regardless of viscosity. So when your oil is overly thick at start-up, and oil pressure is very high, the piston spray jets will be operating very well since the bearings will not accept a lot of cold, thick oil. The rest of the oil will be shared between the valvetrain, piston jets, timing chain jets, and the remainder will leave through the relief valve. So with a hot engine, hot oil, and at idle speed, your piston cooling jets may not be operating very well until the engine RPM is raised up due to lower oil pressure because of thinner (hot) oil.