Viscosity, wear, engine failure, oh my!

[aquariuscsm]

Originally Posted By: OVERK1LL
Originally Posted By: drninja
What about the HM products from Mobil 1? A little more readily available in my area than the 0w40


IMHO, the 0w40 is a better oil. Is it not available at your local Walmart?


How different would you say the M1 0W40 is vs the M1 10W40HM? Are they very close,or completely different from each other?

 

[JOD]

Originally Posted By: drninja

I wonder if there has ever been a catastrophic engine failure in one of these cars that could be conclusively shown to be caused by running a 5w30 "energy conserving" oil. Even your turbo failure could have been caused by any number of factors, including "[censored] happens". I also wonder if anyone has conclusively shown that an energy conserving oil shearing to a high 20-grade is actually detrimental to the health of the engine.

It shouldn't be surprising to anyone that has any knowledge of statistics that there will be a disproportionate # of spun bearings from people using 5w30, since that is what the manual recommends and is what MOST owners will use (this especially applies to the Mobil 1 hysteria since Mobil 1 is the best selling synthetic oil in the US). Also, people won't typically post on a forum to report that their car using 5w30 is running well. They will post when something breaks and they need to vent and ask for advice.

Any thoughts?


My thoughts are that you're right now with this line of thinking. The group-think on the Subaru forums is that Mobil 1 is junk and 5W30 is too thin. Of course, most people use 5W30 since it's specified, and Mobil 1 is the best-selling synthetic. It seems like simple math to me...

I thought the UOA comment was funny. I agree with dOOd's comments regarding the usefulness of UOA's and oil selection, but if you're going to hang your hat on UOA's, there's always this one. Thin, 5W30 Supertech, looking good...

In a high-boost turbo, I think an oil that meets Honda's turbo spec, HTO-06, would be a good choice, changed at a reasonable interval. If you believe the published volatility numbers for Pennzoil Ultra, it looks particularly well-suited to a turbo application. I've yet to see any evidence that a thicker oil than specified is beneficial in this car.

 

[aquariuscsm]

Originally Posted By: JOD
Originally Posted By: drninja

I wonder if there has ever been a catastrophic engine failure in one of these cars that could be conclusively shown to be caused by running a 5w30 "energy conserving" oil. Even your turbo failure could have been caused by any number of factors, including "[censored] happens". I also wonder if anyone has conclusively shown that an energy conserving oil shearing to a high 20-grade is actually detrimental to the health of the engine.

It shouldn't be surprising to anyone that has any knowledge of statistics that there will be a disproportionate # of spun bearings from people using 5w30, since that is what the manual recommends and is what MOST owners will use (this especially applies to the Mobil 1 hysteria since Mobil 1 is the best selling synthetic oil in the US). Also, people won't typically post on a forum to report that their car using 5w30 is running well. They will post when something breaks and they need to vent and ask for advice.

Any thoughts?


My thoughts are that you're right now with this line of thinking. The group-think on the Subaru forums is that Mobil 1 is junk and 5W30 is too thin. Of course, most people use 5W30 since it's specified, and Mobil 1 is the best-selling synthetic. It seems like simple math to me...

I thought the UOA comment was funny. I agree with dOOd's comments regarding the usefulness of UOA's and oil selection, but if you're going to hang your hat on UOA's, there's always this one. Thin, 5W30 Supertech, looking good...

In a high-boost turbo, I think an oil that meets Honda's turbo spec, HTO-06, would be a good choice, changed at a reasonable interval. If you believe the published volatility numbers for Pennzoil Ultra, it looks particularly well-suited to a turbo application. I've yet to see any evidence that a thicker oil than specified is beneficial in this car.



It really does make you wonder,huh! You`ll see ultra-thin oils turning in impeccable UOA`s (there was a Nissan Sentra who had a perfect one on RP 0W10),then thick oils turning in horrible ones. Then you`ll see thick oils turning in flawless UOA`s (there was a Toyota truck with a perfect UOA on M1 15W50 who went almost 15,000 miles) and thin oils with attroicious UOA`s. Could it be that any oil will lubricate an engine perfectly,and it just comes down to "luck of the draw" in getting a properly manufactured engine?

 

[CATERHAM]

Originally Posted By: edhackett
Actually, the Subaru manual does not recommend 5W30 for the use under which most people spun bearings. The manual(2003 WRX and 2008 LGT) clearly states that 5w30 is recommended for best fuel economy. For high temperatures and heavy duty use(that would include track days) they recommend thicker oils up to and including 10W-50 and 20W50. Nobody seems to actually RTFM and get past the required government CAFE brainwashing.
Ed


I don't see any "CAFE brainwashing" going on here.
AFAIK, CAFE requirements don't extend to track day use.
But it an incorrect interpretation of the RTFM to run a heavier oil intended for extreme use if you use you car primarily to get milk at the corner store and otherwise drive in a conservative manner as 99.999% of North Americans do, even those with sporty cars.

 

[45ACP]

Originally Posted By: CATERHAM
Originally Posted By: edhackett
Actually, the Subaru manual does not recommend 5W30 for the use under which most people spun bearings. The manual(2003 WRX and 2008 LGT) clearly states that 5w30 is recommended for best fuel economy. For high temperatures and heavy duty use(that would include track days) they recommend thicker oils up to and including 10W-50 and 20W50. Nobody seems to actually RTFM and get past the required government CAFE brainwashing.
Ed


I don't see any "CAFE brainwashing" going on here.
AFAIK, CAFE requirements don't extend to track day use.
But it an incorrect interpretation of the RTFM to run a heavier oil intended for extreme use if you use you car primarily to get milk at the corner store and otherwise drive in a conservative manner as 99.999% of North Americans do, even those with sporty cars.


I know you talk about the "margin of error" but i think MOST drivers like an oil that can handle that "one time" they open their car up on an open highway, or take that surprise 10+hours trip to a family vacation with the grade of oil they selected.

I know you said its all about a "margin of error" and i can get my head around MOST of that (not all) before but then why does Subaru recommend a 40 or even a 50-grade based on heat, thats why i think OP said its a case of RTFM?

Also, warranty concerns. If not ENGINE LONGEVITY. Maybe the engine is a sludger and the engineers knew that and knew something we dont! Why, then, not.. do what they say.. oh you knew that was coming. Or a turbo. or has higher than normal engine temps like a ZR1 Corvette of the 90s, EVEN DURING NORMAL USE!! ?

I dont get this. heat DOES thin oil a la thicker grade used, then we say heat DOSNT thin oil i dont understand

Also should be noted car does NOT have OP gauge.................
Even BMW has Oil TEMP gauge not Oil PRESSURE gauge..............................................
So it is a mystery............................................
Thought the new Subaru engine spec'd a 20-weight............ a la CAFE brainwashing............. a la FORD......................................................

Need clarification.

 

[CATERHAM]

If one is that interested in motor oil and performance driving you're doing yourself a disservice not to install an oil pressure gauge (an oil temp' gauge is almost as useful). It really does clear-up a lot of false assumptions about what does generate high oil temp's.
The point is, an occational full throttle blast won't cause oil temp's to rise significantly because it can't be sustained.
And cruising at 80 mph on a summer day won't do it either.
It's sustained WOT conditions that can generate high oil temp's and even on a track it can take many laps on a high speed track to generate those higher than normal oil temp's in a car that has a propensity to do so. And the second you take you foot out of it, like on the cool down lap the oil temp's quickly return to normal.

 

[Garak]

Originally Posted By: CATERHAM
And the second you take you foot out of it, like on the cool down lap the oil temp's quickly return to normal.


I think this point is often missed - how rapidly oil temperatures can actually fall.

 

[Cujet]

Lots of good info above.

Speaking from turbo experience, heavier viscosity is often required due to excessive temperatures and the resulting loss of oil pressure and subsequent bearing problems.

Heavier viscosity also has more film strength and can prevent certain bearing problems under severe conditions. Say, for example, a forced induction engine, experiencing detonation, under very high loads.

My favorites for performance car Turbo use in S. Florida:

Mobil 1, 15W-50
Mobil 1, 5W-40 Turbo Diesel Truck (an excellent oil for gas engines)
Mobil 1, 20W-50 V-Twin motorcycle oil. Provides slightly higher oil pressure when compared to the 15W-50 in hot conditions.

I'm not saying these are the best oils. Just that they are very good oils, up to the task and commonly available at any auto parts store. If you need more than this, you need to re-visit your engine parameters.

Some interesting reading:

http://www.substech.com/dokuwiki/doku.php?id=engine_bearing_failure

 

[CATERHAM]

Originally Posted By: Cujet

My favorites for performance car Turbo use in S. Florida:
Mobil 1, 15W-50
Mobil 1, 5W-40 Turbo Diesel Truck (an excellent oil for gas engines)
Mobil 1, 20W-50 V-Twin motorcycle oil. Provides slightly higher oil pressure when compared to the 15W-50 in hot conditions.

What I usually tell my otherwise bright thick oil advocates is to run the heaviest oil with the lowest VI that you want, just don't run you oil pump in by-pass mode. And for those that don't know your oil pump goes into by-pass by diverting the oil flow to the sump and not through the engine when the engine oil is too thick.
Since my otherwise bright thick oil freinds agree that running an engine in by-pass mode is counter-productive, they go along with my suggestion. Of course you must have an oil pressure gauge to determine when the oil pump goes into by-pass.
Well inevitably what happens is that my thick oil freinds tell me there must be something wrong because they can almost never use maximum rev's even when the engine is up to normal operating temp's because the oil pump always goes into by-pass.

I tell them there is nothing wrong, you're simply using a way too heavy oil. All immediately stop using 50wt oil and usually settle on a high VI 40wt oil like M1 0W-40. And a couple of freinds have gone back to running the spec' 5w30, one of which is using 0W-20 for winter use and may continue with it through the summer next year.

 

[TFB1]

You make too much out of the oil bypass issue, it isn't a pop off valve that dumps all the oil volume back into the pan... Sure if it starts to open at 80psi, SOME oil is being diverted to the oil pan, BUT the engine still has 80psi feeding the pressure points and by no means is starving for oil...

I will agree it isn't a optimum condition for a hot engine, especially if a oil several grades thicker than recommended is being used...

 

[CATERHAM]

I didn't mean to imply it's a "pop off" value.
It's the point at which oil flow starts to be diverted and if it occurs with the engine at operating temperature,bearing temperature will start to rise higher than normal due to the reduced flow.
Besides the oil pressure at that point is usually way higher than optimum and using you 80 psi by-pass point example , the engine's optimum operational viscosity may correspond to an OP of 60 psi.

Never running an engine in by-pass mode is a good practice to follow. First the exercise give one first hand experience of when oil is in fact too heavy. And if you find you can't use maximum rev's without going into by-pass well past the point the the engine coolant has reached normal operating temp's too much of the time, you'll ask yourself what's the benefit of running this heavy oil again?

 

[Cujet]

Originally Posted By: CATERHAM
Originally Posted By: Cujet

My favorites for performance car Turbo use in S. Florida:
Mobil 1, 15W-50
Mobil 1, 5W-40 Turbo Diesel Truck (an excellent oil for gas engines)
Mobil 1, 20W-50 V-Twin motorcycle oil. Provides slightly higher oil pressure when compared to the 15W-50 in hot conditions.

What I usually tell my otherwise bright thick oil advocates is to run the heaviest oil with the lowest VI that you want, just don't run you oil pump in by-pass mode. And for those that don't know your oil pump goes into by-pass by diverting the oil flow to the sump and not through the engine when the engine oil is too thick.
Since my otherwise bright thick oil freinds agree that running an engine in by-pass mode is counter-productive, they go along with my suggestion. Of course you must have an oil pressure gauge to determine when the oil pump goes into by-pass.
Well inevitably what happens is that my thick oil freinds tell me there must be something wrong because they can almost never use maximum rev's even when the engine is up to normal operating temp's because the oil pump always goes into by-pass.

I tell them there is nothing wrong, you're simply using a way too heavy oil. All immediately stop using 50wt oil and usually settle on a high VI 40wt oil like M1 0W-40. And a couple of freinds have gone back to running the spec' 5w30, one of which is using 0W-20 for winter use and may continue with it through the summer next year.


With 0.001 clearance on main and rod bearings, plus a 0.030 inch orifice on the turbo oil inlet, the 1.8L turbo miata engine is utterly unable to maintain safe oil pressure levels when operating during "track days" and in heavy traffic in South Florida without the use of a higher viscosity oil. Same goes for aircraft engines. But, hey, what do I know... Just throw a bigger oil pump on it, right?

With the air temps over the black highway well North of 100 degrees F on a normal day, and around 120 on a mid summer day, oil viscosity is a key to success.

You will find many moderately built turbo engines living normal lives on 5w30 synthetic or even 0W-30. However, you won't find as many thin oil success stories when the HP/displacement ratio exceeds 200HP/L. When the HP/L ratio is knocking on 250HP/L on production based engines, thin oils are downright unable to provide track day protection, especially on hot days.

Ontario may be just slightly different than South Florida, no?

 

[A_Harman]

I'm not familiar with the range of clearances on Mazda engines, but .001" sounds like it would be on the tight side. My Cosworth Vega (2.0-L DOHC I4) specified clearances in the range of .0020-.0025" on both the rods and mains. Tight bearing clearances restrict oil flow, increase film thickness, and decrease film pressure. This is all good for high-performance engines.

Adding the turbo to the oil system does increase the capacity requirement, though. Maybe the original Mazda pump wasn't sized to provide additional flow to a turbo? What oil temperatures are you running? Maybe the oil is thinning excessively and losing viscosity as a result. Does your car have an oil cooler?

 

[d00df00d]

Originally Posted By: Cujet
With 0.001 clearance on main and rod bearings, plus a 0.030 inch orifice on the turbo oil inlet, the 1.8L turbo miata engine is utterly unable to maintain safe oil pressure levels when operating during "track days" and in heavy traffic in South Florida without the use of a higher viscosity oil. Same goes for aircraft engines. But, hey, what do I know... Just throw a bigger oil pump on it, right?

With the air temps over the black highway well North of 100 degrees F on a normal day, and around 120 on a mid summer day, oil viscosity is a key to success.

You will find many moderately built turbo engines living normal lives on 5w30 synthetic or even 0W-30. However, you won't find as many thin oil success stories when the HP/displacement ratio exceeds 200HP/L. When the HP/L ratio is knocking on 250HP/L on production based engines, thin oils are downright unable to provide track day protection, especially on hot days.

Ontario may be just slightly different than South Florida, no?

In those higher temps with those bigger clearances, CATERHAM's method would indicate that a thicker oil would be optimal. So, really, your comments and his are not mutually exclusive as-written.

 

[edhackett]

Quote:
Thanks for the reply. I agree that under the conditions most of these folks are spinning bearings, they should be using a higher grade oil than recommended. In your opinion, do you think a stock WRX driven under daily-driver conditions would require a thicker oil? Many on NASIOC seem to think so.


I think so. The manual specifically calls out desert areas for the higher viscosity oils. Texas and Nevada qualify.

Engines like the Subaru turbo put out a lot of torque at low rpm. You can put a lot of stress on the bottom end by just flooring it at 2000 rpm to make a pass on the street.

That said, I have never run a XW-40 in either my WRX or LGT. I have always used oils that have a HTHS viscosity of at least 3.5. I have run GC,and currently Rotella T5 10W-30 in the Legacy. This choice was recently supported here a couple of weeks ago by a post where less bottom cylinder wear(gravity is a factor in horizontal engines) was seen via bore scope with cars that had run a >3.5 HTHS oil. I don't know if that comes from the HTHS or the generally more robust additive packages that come with the non energy conserving oils. It doesn't really matter, both can reduce wear.

Unless they are running an oil thicker than a 20W-50, they aren't running a higher grade than recommended. That's where the brainwashing I mentioned comes in. The "recommended" verbage in the manual and the the numbers on the oil filler cap are mandated by federal regulation to be the viscosity used to obtain the vehicles CAFE numbers. It's not the best oil viscosity for the engine period. People don't get past the "recommended" to read the foot note or the next paragraph. They just assume "recommended" means best and stop there. For the vast majority of vehicles that is a good all around choice. We have seen families of engines here that do better on other than the CAFE oil, Subaru turbos among them, IMHO.

Ed