My experiences with thin oil

[Doug Hillary]

Hi,
CIRHS - You said this:
"What is the oil film strength of say xw20 compared to xw40 or xw30 oil and has anyone done a UOA to campare engine wear with thin oils?"

It is wise searching on here as this matter has been long discussed over several years
The ACEA Quality rating system clearly spells this out and the API are now playing catchup along similar lines

AEHAAS - Less viscous lubricants have long demonstated an ability to stay in grade and the 20W-20 lubricants of the past (even 50 years ago) had a great reputation in this regard. The latest lubricants are indeed great products but it is always a case of "horses for courses"

You said this:
"Also, when you talk about viscosity you must at the same time talk about oil temperatures. A 20 grade oil at 180 F has about the same viscosity as a 30 grade at 200 F and about the same viscosity of a 40 grade oil at 220 F and so on."

This is true and in many Porsche engines an SAE50 lubricant (say 15W-50) will spend much of its life at a bulk temperature of around 90C and at a viscosity nearing SAE60! This does nothing for the optimal operating efficiency of an engine that should have a SAE40 lubricant (say 0W-40)

That is one side of the equation - the other side is the lubricant's operating and "return to bulk" temperatures. IMHE this raises the importance of the HTHS viscosity. The lubricant spends much of its time a long way from the bulk temperature and I have measured many engines where this is way beyond 150C and in those areas where external temperatures cannot be taken, much much hotter!

Insufficient HTHS viscosity will indeed cause wear and this will not be reflected via UOAs - even the ACEA Test parameters indicate this

Using the less viscous of those lubricants Approved and Listed by the engine manufacturer will provide the best likelihood of optimal operating efficiency and the enhanced fuel economy and performance that goes with it

As an example most Mercedes Benz engine families allow all year round (30C) (86F) use of from 0W-30 to 5W-50 synthetic lubricants from their List of Approved lubricants

Some engines do need to have a HTHS viscosity at at least the minimum number prescribed by the engine's manufacturer. IMHO it is unwise to go under this for any length of time and to expect the ultimate in long term durability!

You said this too:
"If you race your BMW with sump temperatures of 290 F then it would be safe to use a 20 grade oil if the sump was 180 F."

I have some difficulty with this......................................? You do not mention the HTHS viscosity and the lubricant's ability to maintain it

 

[AEHaas]

Ten and more years ago tests of non fully formulated oils showed that there was more wear when the HTHS was less than 3.5. Now there are 20 grade oils used in towing trucks where the HTHS is 2.6. Yet over the last 5 - 8 years there is no evidence of elevated wear. I for one just do not pay attention to HTHS.

I have not seen any wear analysis of fully formulated Current oils and HTHS wear. There must be a reason for this. And whereas those who test engines at GM have continued to look at (100 C) viscosity and temperature as a factor of engine wear these same people just do not seem to be interested in HTHS.

aehaas

 

[jaj]

Originally Posted By: OVERK1LL
...In discussing engines with factory 40 and 60 weight recommendations (Porsche and BMW) would one not have to consider these same issues you encountered in terms of wear due to bore finish, ring tension and bearing material when switching these engines to a lighter grade?

Edit: to extrapolate:

What I am trying to get at here is that perhaps the "run lighter oil" argument is being oversimplified by its proponents.

And of course this brings us back to Doug's suggestion of running the lightest weight oil suitable for the prevailing ambient conditions as specified by the engine manufacturer.



The interesting but oft-forgotten fact is that when BMW brought the E46 M3 with the S54 engine to North America in 2000 it was factory filled with (and had a service-lube sticker for) BMW High Performance Synthetic Oil 5w-30. Further, in 2001, BMW dropped the E39 M5 requirement from 10w-60 back to 5w-30 as well (they never went back for the M5 engine). Effectively, the entire BMW fleet, including the M-cars were using 5w-30. Were it not for the mechanical problems the M3 had in 2001 and 2002, you have to wonder if 10w-60 would have been used in any BMW engines in North America today.

However, when E46 engines started blowing up in 2001, the first thing BMW did was switch the S54 engines to 10w-60, and they stayed with that spec for the life of the product. (can you hear the sound of the parts logistics guys losing a bet with the engineers? What's German for "we told you so!")

In the end, all of the blow-ups were traced to manufacturing problems - casting sand left in the block or mis-manufactured bearings.

All new "M-division" engines from 2001 to the present (the 8,200 RPM 5 liter V10 and the new 8,400 RPM 4-liter V8) use Castrol TWS Motorsport 10w-60 exclusively. Were it not for the manufacturing problems with the M3 engine, what oil would they be using?

 

[Doug Hillary]

Hi,
AEHaas - Well no doubt you have your viewpoint - and I have mine!

I will not be using any lubricant that has a lessor HTHS viscosity than the minimum mandated by the engine's manufacturer any time soon - regardless of the lubricant's published viscosities at both 40C and 100C

I have a lot of faith in the ACEA Test principles and those of the engine manufacturers - based on around 50 odd years of experience in the design, manufacture, application and end use of both petrol and diesel engines - from NA, Europe and Japan

 

[OVERKILL]

Originally Posted By: jaj
Originally Posted By: OVERK1LL
...In discussing engines with factory 40 and 60 weight recommendations (Porsche and BMW) would one not have to consider these same issues you encountered in terms of wear due to bore finish, ring tension and bearing material when switching these engines to a lighter grade?

Edit: to extrapolate:

What I am trying to get at here is that perhaps the "run lighter oil" argument is being oversimplified by its proponents.

And of course this brings us back to Doug's suggestion of running the lightest weight oil suitable for the prevailing ambient conditions as specified by the engine manufacturer.



The interesting but oft-forgotten fact is that when BMW brought the E46 M3 with the S54 engine to North America in 2000 it was factory filled (and had a service-lube sticker for) BMW High Performance Synthetic Oil 5w-30. Further, in 2001, BMW dropped the E39 M5 requirement from 10w-60 back to 5w-30 as well (they never went back for the M5 engine). Were it not for the mechanical problems the M3 had in 2001 and 2002, you have to wonder if 10w-60 would have been used in later engines.

However, when E46 engines started blowing up in 2001, the first thing BMW did was switch the S54 engines to 10w-60, and they stayed with that spec for the life of the product. (can you hear the sound of the parts logistics guys losing a bet with the engineers? What's German for "we told you so!")

In the end, all of the blow-ups were traced to manufacturing problems - casting sand left in the block or mis-manufactured bearings.

All new "M-division" engines from 2001 to the present (the 8,200 RPM 5 liter V10 and the new 8,400 RPM 4-liter V8) use Castrol TWS Motorsport 10w-60 exclusively. Were it not for the manufacturing problems with the M3 engine, what oil would they be using?





That's a very good question! I'm amazed they did not pull a Porsche/Mercedes and go for something like a 5w or 0w40....

 

[Bryanccfshr]

Modern low friction low pressure valvetrains and improvements in machining make HTHS less and less of an issue. Reliance onhigher HTHS for protection is an indicator of older technology.

 

[Doug Hillary]

Hi,
Bryanccfshr - At the upper temperature boundaries the viscosity of the lubricant is extremely important - it is still the difference between metal to metal or contaminant to metal abrasion - and ever more so as working loads and oil temperatures increase

 

[jaj]

Originally Posted By: Bryanccfshr
Modern low friction low pressure valvetrains and improvements in machining make HTHS less and less of an issue. Reliance onhigher HTHS for protection is an indicator of older technology.


I would respectfully disagree - it may be "older" technology or it may be "more predictable because of years of experience" technology. The latest pair of BMW "M" engines, the V10 and V8, are "new from the ground up" designs from BMW. In Europe, the V10 launched in 2005 and the V8 in 2007. They are "family" in the sense that they share the same design with a different cylinder count and a few minor external changes (high-pressure versus low-pressure VANOS for instance).

How do we know they're new and not just an upgrade to an existing engine family? They were the first of the BMW "bedplate" engines that use a full-length ladder-frame in place of traditional main-bearing caps used on other BMW (and most of the rest of the world's) engines. (BMW also uses this bedplate technology in their N52 magnesium-block inline 6's as well) The new V-engines have a short-stroke design with a forged crank locked in an extremely rigid cylinder block. The two new engines share parts with each other, but not with anything else BMW produces. They're about as state-of-the-art as you can get with engine designs.

Hence my point at the beginning - BMW's designers had the opportunity to change everything with these new engines, and mostly they did. What they didn't change though was the specified engine oil: TWS 10w-60 with an HTHS of 5.2! Is that because it's old technology, or is it because it's known to work well and ensure the kind of durability and longevity expected from a production road-going engine?

 

[vinu_neuro]

BMW's use of 10W-60 in the M engines might have to do with the hypereutectic Al-Si bore material they use in those blocks. That bore material wears significantly more than iron. The pistons and rings have slightly elevated wear comparatively too. I don't know why they don't just use a Metal Matrix like Honda which is has the advantages without the poor wear.

 

[Bryanccfshr]

In NA service oil temperatures rarely get to 100c. As far as contaminant to metal contact, this is the function of a proper air and oil filtration systems. If you are getting solids large enough that libricant film thickness is your last layer of protection the engine is going to suffer anyhow.
Metal to metal contact under heavy loads. I don't see an example in non commrcial (or emergency power generation)applications s that would put that kind of low rpm high torque load on a vehicle. Most applications that allow for 20 wt oils have low pressure low friction valvetrains as well as either light vehicle sand easy gearing or automatic transmissions that do not allow shockloading. My jeep runs 5w20 with a manual 6 speed I don't worry about shockloading offroad due to gearing torque multiplication advantages.
I have yet to see a failure nor evedince of early wear in vehicles that have been recomended for 5 or 0w20 oils that have run it.

My work truck is a 2006 Ford F150. It is one of many Ford trucks running the oilfield roads constantly with 5w20. They are running offroad in dusty,muddy,snow mud chain conditions and we are maxxing out the GVW's on many of them(we have gasser 250's and 350's too) all running the 5w20. Our fleet shop manager just went to using synthetic this year at my current work location. It is snowing now but in the summer it is deser southwest. Fleet manager hasn't had any oil related failures but he says we have so much dust he is conservativewith oil and filtrtation maintenance.

 

[Bryanccfshr]

I too consider BMW's metallurgy questionable in that engine family. Of course basing ones faith in a poorly put together engine family is not good logic.

 

[Doug Hillary]

Hi,
Bryanccfshr - You said;
"I have yet to see a failure nor evedince of early wear in vehicles that have been recomended for 5 or 0w20 oils that have run it."

And neither have I!

I have consistently recommended using the lower viscosity of those recommended and Approved and Listed by the engine's manufacturer - according to the spread of ambient temperature of course

 

[Bryanccfshr]

What was this thread about??

 

[HTSS_TR]

Originally Posted By: Bryanccfshr

What was this thread about??

Thinner oil in engine spec'd for thicker oil.

 

[OVERKILL]

Originally Posted By: Bryanccfshr
In NA service oil temperatures rarely get to 100c. As far as contaminant to metal contact, this is the function of a proper air and oil filtration systems. If you are getting solids large enough that libricant film thickness is your last layer of protection the engine is going to suffer anyhow.
Metal to metal contact under heavy loads. I don't see an example in non commrcial (or emergency power generation)applications s that would put that kind of low rpm high torque load on a vehicle. Most applications that allow for 20 wt oils have low pressure low friction valvetrains as well as either light vehicle sand easy gearing or automatic transmissions that do not allow shockloading. My jeep runs 5w20 with a manual 6 speed I don't worry about shockloading offroad due to gearing torque multiplication advantages.
I have yet to see a failure nor evedince of early wear in vehicles that have been recomended for 5 or 0w20 oils that have run it.

My work truck is a 2006 Ford F150. It is one of many Ford trucks running the oilfield roads constantly with 5w20. They are running offroad in dusty,muddy,snow mud chain conditions and we are maxxing out the GVW's on many of them(we have gasser 250's and 350's too) all running the 5w20. Our fleet shop manager just went to using synthetic this year at my current work location. It is snowing now but in the summer it is deser southwest. Fleet manager hasn't had any oil related failures but he says we have so much dust he is conservativewith oil and filtrtation maintenance.


Bryan:

You are simply reinforcing Doug's point about using the thinnest oil grade for the predominant ambient conditions specified by the engine manufacturer.

And the topic of bore finish, ring tension and material, bearing material, clearances and the like are all factors here. As very well illustrated by tdi-rick's examples.

Nobody is arguing that a 5w20 or 0w20 is an inadequate lubricant. Obviously it works well in the engines spec'd for it. I think the point of question here is about its use in applications where it is not spec'd by the manufacturer and a much heavier grade IS.

 

[Bryanccfshr]

Somehow I allowed myself to drift off that topic into the worn out generalities of thin oil use. I am in the middle of a new position and move so my focus has not been what it should be.
I agree that to go out of manufacturers specification on oil viscosity or even approvals is not well advised without the owner understanding the risk they are taking.

 

[jaj]

Originally Posted By: vinu_neuro
BMW's use of 10W-60 in the M engines might have to do with the hypereutectic Al-Si bore material they use in those blocks. That bore material wears significantly more than iron. The pistons and rings have slightly elevated wear comparatively too. I don't know why they don't just use a Metal Matrix like Honda which is has the advantages without the poor wear.


I suspect BMW's reasoning is more like "we don't see any reason to change the spec" than anything else. The origins of the TWS at BMW are with the Motorsport (racing) division and they use it in lots of purpose-built racing engines. I imagine that after the debacle with the M3 engines blowing up, the "experiment" with 5w-30 in high-rev engines was over and the accountants relented and allowed the engineers to specify ONE "special" oil for M engines. Well, once you have the dealership logistics chain in place to deliver a "special" oil product, you can make it anything you want, just so long as you don't have the impudence to ask the accountants for a second "special" oil. What did they pick? The Motorsport division favorite - TWS.

The BMW TWS 10w-60 is (I believe - Doug correct me if I'm wrong) the Castrol oil that Doug Hillary knows so well - it's good stuff and has been since the mid-90's when it came on the market at API SJ Castrol Racing Syntec RS 10w-60. BMW acquired an exclusive license to the SJ formula and rebranded it as TWS but didn't otherwise change it in 2000 when Castrol reformulated their retail RS-branded product. Five years later, presumably when the exclusive ran out, Castrol introduced "Edge 10w-60", an API SJ oil that's approved for "M" engines. Sounds hauntingly familiar, no?

As for the metallurgy, the S65/S85 V-engines use iron-coated forged pistons in Alusil bores. Basically, it's the traditional design turned inside out and made really light. I imagine it's easy to manufacture, too. As for longevity, we'll have to wait and see. The previous edition M3 engine, the S54 inline six, was based on a cast-iron block and it stood up pretty well. I know that Mercedes Benz used Alusil blocks in the 1990's vintage M119 engines and those things would last forever if you kept the oil clean.

 

[jaj]

Originally Posted By: Bryanccfshr
Somehow I allowed myself to drift off that topic into the worn out generalities of thin oil use. I am in the middle of a new position and move so my focus has not been what it should be.


I guess I wandered off too - my point with the BMW story is that the manufacturer actually switched their high-performance engines to a lower viscosity oil in the early 2000's. The experiment appeared to "fail" when engines started blowing up, so they switched back to high viscosity oil and have stayed with it ever since, including their brand-new engine families.

However, the facts were that the experiment didn't really fail - the blown engines were not the result of a lubrication problem, just a manufacturing problem. Because the experiment was cut short when they switched the fleet back to 10w-60, we'll never know what would have happened. If a large fleet of BMW "S" engines worked fine in North America with 5w-30 compared with the rest of the world running 10w-60, we'd have had a large-scale demonstration of Dr. Haas' point about thin oils being as good as or better than thick oils.

 

[Bryanccfshr]

The manufacturing quality issues with that engine put an interesting twist on the story. I agree, without that issue the 5w30 in the M3 may very well have succeed in the NA market

 

[Doug Hillary]

Hi,
jaj - Yes I can confirm the TWS heritage commencing with it as a castor base lubricant 15W-50 in the mid 1970s. Later as Castrol Formula R 10W-60 it was used by Sauber-Mercedes in winning the '89 and '90 WSC Champs (and Le Mans in'89), HB Cosworth engines, Jaguar and by Porsche and BMW. It was and still is an excellent lubricant even in some racing gearboxes too - including six speed ZFs

Alusil and some variants has proven to be wonderful in Porsche (M28 and others) and Benz engines. The structure with the protruding silicate particals "captures" and retains the lubricant in the walls. Many Porsche V8 M28 engines have now neared 1m miles without attention in that regard. Some Benz V8 engines from the "same" family (SL and SEC Models) that live around here are in excellent condition with minimal lubricant use at around 500kkms

I can also confirm that BMW's "issue" with the specific "M" engines was caused by imperfect production matters - mainly from third party supplier(s). It was a lubrication system problem and not a lubricant problem (the HTHS comments in this Thread add some insight). Using the 10W-60 lubricant with a very robust HTHS viscosity was a cheap and excellent "fix"

Best wishes for 2009 jaj!