And do note we don't have a lot of durability issues, even with conventional, either.
Engine Oil Viscosity - wasted energy during warmup
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Fully agree. Bearing wear, cam wear, ring wear all no problem even with the worst dino.
However piston deposit build-up can be slow and you can't see it (not without dismantling your engine anyway). There's nothing on a Blackstone analysis that can tell you about an oil's propensity to lay down deposits either. First ring and second ring, whilst traditionally the 'dirty' rings I wouldn't worry about too much as their groove action tends to keep them free. The oil control ring is the killer.
However piston deposit build-up can be slow and you can't see it (not without dismantling your engine anyway). There's nothing on a Blackstone analysis that can tell you about an oil's propensity to lay down deposits either. First ring and second ring, whilst traditionally the 'dirty' rings I wouldn't worry about too much as their groove action tends to keep them free. The oil control ring is the killer.
That's true, but to be fair, we did quite well with the taxis, even hitting 1,000,000 km. The pistons didn't do too badly, but generally speaking, things were reasonably clean, running on LPG.
Originally Posted By: camrydriver111
Interesting points.
I wonder if the oil change culture has something to do with it. In the US people used to change oil ever 3k mi and now every 5k mi. Which is better than 3k, but still very short. In Europe what is the most common OCI? 12k mi? If long drain intervals were adopted in the US the oil specs would have to change.
European brands are well over 12k... 20k would be about average these days. Asian cars have shorter oci's, 10-12k on average.
Interesting points.
I wonder if the oil change culture has something to do with it. In the US people used to change oil ever 3k mi and now every 5k mi. Which is better than 3k, but still very short. In Europe what is the most common OCI? 12k mi? If long drain intervals were adopted in the US the oil specs would have to change.
European brands are well over 12k... 20k would be about average these days. Asian cars have shorter oci's, 10-12k on average.
LPG engines are AMAZINGLY clean! I swear you could put rancid chip fat in an LPG engine and it would still look pristine after 50,000 miles.
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Originally Posted By: Garak
That's true, but to be fair, we did quite well with the taxis, even hitting 1,000,000 km. The pistons didn't do too badly, but generally speaking, things were reasonably clean, running on LPG.
Originally Posted By: Joe90_guy
Fully agree. Bearing wear, cam wear, ring wear all no problem even with the worst dino.
However piston deposit build-up can be slow and you can't see it (not without dismantling your engine anyway). There's nothing on a Blackstone analysis that can tell you about an oil's propensity to lay down deposits either. First ring and second ring, whilst traditionally the 'dirty' rings I wouldn't worry about too much as their groove action tends to keep them free. The oil control ring is the killer.
+1
That's true, but to be fair, we did quite well with the taxis, even hitting 1,000,000 km. The pistons didn't do too badly, but generally speaking, things were reasonably clean, running on LPG.
Originally Posted By: Joe90_guy
Fully agree. Bearing wear, cam wear, ring wear all no problem even with the worst dino.
However piston deposit build-up can be slow and you can't see it (not without dismantling your engine anyway). There's nothing on a Blackstone analysis that can tell you about an oil's propensity to lay down deposits either. First ring and second ring, whilst traditionally the 'dirty' rings I wouldn't worry about too much as their groove action tends to keep them free. The oil control ring is the killer.
+1
I noticed when visiting the shop that did my machine work was that almost every engine they had torn down had a lot of deposits around oil control rings. The grooves were filled with crud. Is this a weak link in lubrication that would lead to other wear/lubrication problems?
it'll lead to oil consumption issues, which can lead to failure if not followed closely.
Thanks for sharing this. Right now I'm big on theory but very short on hard facts.
In my mind, what I'm imagining is that high Noack volatility US oils are pushing volatilised, 'fractionated' oil through the PCV into the intake system to be burnt. This process will be exacerabated by fuel dilution or water condensation in the sump. The residual garbage from burning this oil is, I believe, a primary cause of piston deposits. I call these 'over-the-top' deposits.
Normally you see deposits limited to the first groove but if this goes in for long enough, those deposits will migrate down the piston and hit the oil control ring. The top and second rings are self-freeing and to a certain extent self cleaning because they are constantly expanding (on the compression stroke) and retracting (on the other strokes). They also constantly rotate so abrade crud in the groove. The oil control ring does none of these things. Crud that accumulates will tend to 'bake' and cause the three parts of the oil control ring to 'fuse' into the piston.
Once this happens, the mechanism of oil loss changes and you will get severe 'bottom-up' oil loss. The cylinder bore is sprayed/splashed with bulk oil on the piston up-stroke. Normally the oil control ring reduces this to a very thin film of oil on the down stroke. However if this thinning doesn't happen, on the down stroke, hydraulic pressure builds up in the piston-bore gap and will force bulk oil through the second and first ring gaps into the combustion chamber to be burnt. When this happens you're in big trouble!
Just my own personal thoughts based on no evidence whatsoever...
In my mind, what I'm imagining is that high Noack volatility US oils are pushing volatilised, 'fractionated' oil through the PCV into the intake system to be burnt. This process will be exacerabated by fuel dilution or water condensation in the sump. The residual garbage from burning this oil is, I believe, a primary cause of piston deposits. I call these 'over-the-top' deposits.
Normally you see deposits limited to the first groove but if this goes in for long enough, those deposits will migrate down the piston and hit the oil control ring. The top and second rings are self-freeing and to a certain extent self cleaning because they are constantly expanding (on the compression stroke) and retracting (on the other strokes). They also constantly rotate so abrade crud in the groove. The oil control ring does none of these things. Crud that accumulates will tend to 'bake' and cause the three parts of the oil control ring to 'fuse' into the piston.
Once this happens, the mechanism of oil loss changes and you will get severe 'bottom-up' oil loss. The cylinder bore is sprayed/splashed with bulk oil on the piston up-stroke. Normally the oil control ring reduces this to a very thin film of oil on the down stroke. However if this thinning doesn't happen, on the down stroke, hydraulic pressure builds up in the piston-bore gap and will force bulk oil through the second and first ring gaps into the combustion chamber to be burnt. When this happens you're in big trouble!
Just my own personal thoughts based on no evidence whatsoever...
Originally Posted By: Joe90_guy
Once this happens, the mechanism of oil loss changes and you will get severe 'bottom-up' oil loss. The cylinder bore is sprayed/splashed with bulk oil on the piston up-stroke. Normally the oil control ring reduces this to a very thin film of oil on the down stroke. However if this thinning doesn't happen, on the down stroke, hydraulic pressure builds up in the piston-bore gap and will force bulk oil through the second and first ring gaps into the combustion chamber to be burnt. When this happens you're in big trouble!
I'll dig up a link I've got somewhere on piston ring belt residence time, and it was quite shocking that when they put tracer in the oil, the residence time in the ring belt was 10s of seconds, not just a quick fly through. 10s of seconds is forever for the gramme or so of oil in the ring belt, so plenty of time for distillation to take place.
Evidence of much higher additive concentrations in the ring belt, again indicating that the oil is either going AWOL, or turning into something that's no longer liquid.
Further, my pet (educated) theory on varnish has always been that it's formed in the cylinder area, where blowby with it's highly reactive species (NOx, CO, etc.) are working hard against the oxidation stability of the oil.
I've put up that chart before that shows the "average"/common loads/revs for US versus Euro driving, so longer periods with more revs, and more load give you higher ring belt temperatures, higher blowby. etc.
Different courses, so the typical US GF-5 lube may well not cause problems in that world.
Here's the link...note, someone else's work.
Once this happens, the mechanism of oil loss changes and you will get severe 'bottom-up' oil loss. The cylinder bore is sprayed/splashed with bulk oil on the piston up-stroke. Normally the oil control ring reduces this to a very thin film of oil on the down stroke. However if this thinning doesn't happen, on the down stroke, hydraulic pressure builds up in the piston-bore gap and will force bulk oil through the second and first ring gaps into the combustion chamber to be burnt. When this happens you're in big trouble!
I'll dig up a link I've got somewhere on piston ring belt residence time, and it was quite shocking that when they put tracer in the oil, the residence time in the ring belt was 10s of seconds, not just a quick fly through. 10s of seconds is forever for the gramme or so of oil in the ring belt, so plenty of time for distillation to take place.
Evidence of much higher additive concentrations in the ring belt, again indicating that the oil is either going AWOL, or turning into something that's no longer liquid.
Further, my pet (educated) theory on varnish has always been that it's formed in the cylinder area, where blowby with it's highly reactive species (NOx, CO, etc.) are working hard against the oxidation stability of the oil.
I've put up that chart before that shows the "average"/common loads/revs for US versus Euro driving, so longer periods with more revs, and more load give you higher ring belt temperatures, higher blowby. etc.
Different courses, so the typical US GF-5 lube may well not cause problems in that world.
Here's the link...note, someone else's work.
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Thanks for sharing the link. I need time to digest this.
However something has popped into my mind which may or may not be true but is nevertheless bothering me. It's that oil formulators might have twigged that they can beat the all of the API tests with Group II and keep just inside the US Noack limit by throttling back on the amount of ashless dispersant in the oil. If this is indeed credible, it will significantly decrease the ability of the oil to counter any deposit problems. Just like VW, it would be a case of 'beating the tests' but sticking two fingers up at the real life problems in the field. God, do I hope I'm wrong on this!
However something has popped into my mind which may or may not be true but is nevertheless bothering me. It's that oil formulators might have twigged that they can beat the all of the API tests with Group II and keep just inside the US Noack limit by throttling back on the amount of ashless dispersant in the oil. If this is indeed credible, it will significantly decrease the ability of the oil to counter any deposit problems. Just like VW, it would be a case of 'beating the tests' but sticking two fingers up at the real life problems in the field. God, do I hope I'm wrong on this!
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This is interesting to me, but I have a couple issues.
It is interesting because I had a toyota in the '80s that would not shift into top gear until the coolant temp was at least 140F.
My current SUV holds each gear longer and doesn't lock the TC until it is up to temp.
My issue with this is that my SUV has pretty severe cold piston slap until the oil reached about 150F, due to this, I try to keep RPM low until it goes away, which is about 15 minutes into driving - but I live on the edge of a highway - so I pull out of my driveway, go to the end of the street and then have to merge with 70-80MPH traffic - unfortunately I am in the middle of a bend so I can't see who's coming and they can't see me. I would like to accelerate gradually to 80MPH (you know - over like 15 or 20 seconds instead of 10), but this causes people giving me nasty signs and flashing their lights at me. This has not caused any issues, it hasn't gotten noticeably worse in the last 130K miles, but it is worrying none the less.
I believe that the gear holding, etc., is to get the cats hot quickly but I am concerned that it is causing more wear due to increased RPM before the oil is up to temp and working properly as well as the clearances being out of whack due to the metals not being at a stable operating temp.
BMW has had cars in the past that will lower the redline until the oil is hot.
I have always believed that you should warm up a car gently - not pull out into traffic and hold it at 5,000 rpm with cold parts and oil.
I have no doubt that the oil will get up to temp more quickly at high RPM, but at what cost to component longevity?
Will there be more wear occuring in the quicker warm up at high rpm than a normal low rpm warmup? What is the threshold. My SUV has a 300hp 32valve V8 which it holds around 3K until it is warmed up. Is 3K ideal. I would prefer 2K while cold.
With my G35, I stay below 5K until it is warm. The FX I would rather stay at 2K while it is making all the diesel noise.
Something else that may be a non issue for DoubleWasp and I, is that being in south florida, our oil starts at 85F in the morning. We don't have to deal with getting oil up from freezing.
It is interesting because I had a toyota in the '80s that would not shift into top gear until the coolant temp was at least 140F.
My current SUV holds each gear longer and doesn't lock the TC until it is up to temp.
My issue with this is that my SUV has pretty severe cold piston slap until the oil reached about 150F, due to this, I try to keep RPM low until it goes away, which is about 15 minutes into driving - but I live on the edge of a highway - so I pull out of my driveway, go to the end of the street and then have to merge with 70-80MPH traffic - unfortunately I am in the middle of a bend so I can't see who's coming and they can't see me. I would like to accelerate gradually to 80MPH (you know - over like 15 or 20 seconds instead of 10), but this causes people giving me nasty signs and flashing their lights at me. This has not caused any issues, it hasn't gotten noticeably worse in the last 130K miles, but it is worrying none the less.
I believe that the gear holding, etc., is to get the cats hot quickly but I am concerned that it is causing more wear due to increased RPM before the oil is up to temp and working properly as well as the clearances being out of whack due to the metals not being at a stable operating temp.
BMW has had cars in the past that will lower the redline until the oil is hot.
I have always believed that you should warm up a car gently - not pull out into traffic and hold it at 5,000 rpm with cold parts and oil.
I have no doubt that the oil will get up to temp more quickly at high RPM, but at what cost to component longevity?
Will there be more wear occuring in the quicker warm up at high rpm than a normal low rpm warmup? What is the threshold. My SUV has a 300hp 32valve V8 which it holds around 3K until it is warmed up. Is 3K ideal. I would prefer 2K while cold.
With my G35, I stay below 5K until it is warm. The FX I would rather stay at 2K while it is making all the diesel noise.
Something else that may be a non issue for DoubleWasp and I, is that being in south florida, our oil starts at 85F in the morning. We don't have to deal with getting oil up from freezing.
Originally Posted By: Joe90_guy
LPG engines are AMAZINGLY clean! I swear you could put rancid chip fat in an LPG engine and it would still look pristine after 50,000 miles.
We were running the taxis on 10,000 km OCIs back in the late 1970s into the 1990s (and beyond) on conventional Quaker State. And they certainly stayed clean!
LPG engines are AMAZINGLY clean! I swear you could put rancid chip fat in an LPG engine and it would still look pristine after 50,000 miles.
We were running the taxis on 10,000 km OCIs back in the late 1970s into the 1990s (and beyond) on conventional Quaker State. And they certainly stayed clean!
I've had a chance to digest that paper now. I also found a link to a PowerPoint presentation from the same team which makes excellent reading....
http://www.york.ac.uk/res/gkg/posters/Additive_05_Moray_Stark.ppt
What surprised me was that I vaguely knew one of the authors of this paper. Harold Gillespie had retired from Shell when I met him but in his day, he was pretty high up in the Shell Thornton R&D hierarchy. One thing I'll never forget was that he'd just bought himself a new Audi which used an inordinate amount of engine oil. Oh the irony!
The paper makes for interesting reading. It clearly points to the ring pack as being a viable chemical reactor for base oil oxidation with the effects of this slowly washing down to the sump. However I think they missed one thing and that's the chemical reactor that sits above the piston; the combustion chamber. You have high temperature, high pressure and lots of oxygen...all perfect for clobbering oil! I suspect this simple research engine had no PVC system to think about.
http://www.york.ac.uk/res/gkg/posters/Additive_05_Moray_Stark.ppt
What surprised me was that I vaguely knew one of the authors of this paper. Harold Gillespie had retired from Shell when I met him but in his day, he was pretty high up in the Shell Thornton R&D hierarchy. One thing I'll never forget was that he'd just bought himself a new Audi which used an inordinate amount of engine oil. Oh the irony!
The paper makes for interesting reading. It clearly points to the ring pack as being a viable chemical reactor for base oil oxidation with the effects of this slowly washing down to the sump. However I think they missed one thing and that's the chemical reactor that sits above the piston; the combustion chamber. You have high temperature, high pressure and lots of oxygen...all perfect for clobbering oil! I suspect this simple research engine had no PVC system to think about.
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