UOA vs. Actual Bearing wear

[JohnAnthony]

want to share this from M5Board, where we've had string of Rod Bearing failures in the V8 & V10 Motorsport engines

S62B50 V8
S85B50 V10

both engines are recommended Castrol TWS (10W60), but regardless of the oil used whether 30 weight or 60 weight the UOAs for well maintained cars all come back with the same level of Copper & Lead ~1ppm - 6ppm for both

here's a member (2nd owner) whom planned on doing preventative bearing change and he sent the oil that was in there to blackstone for analysis and what they found was nothing out of the ordinary.

http://www.m5board.com/vbulletin/e60-m5-e61-m5-touring-discussion/283882-rod-bearings-50k-miles.html

Image of Rod Bearings:
http://www.m5board.com/vbulletin/e60-m5-...tml#post3508129
Blackstone UOA:
http://www.m5board.com/vbulletin/e60-m5-...tml#post3516913


so what are your inputs on this outcome and oil analysis in general?

P.S. not singling out blackstone they just happened to be the place this member sent his oil

 

[440Magnum]

Wear particles too large to show up on a blackstone UOA? Wear all happened earlier in the life of the engine, and no CURRENT wear was occurring? (I doubt that...)

Definitely shows the limitations of a $30 UOA in reflecting the condition of the engine in general. And as a side-comment... the original ~140,000 mile rod bearings on my '69 440 looked about like that when I pulled them in the late 1990s. No strange noises, good oil pressure at tthe time, but the upper half shells were worn through the babitt into the copper. There's no question that the upper half-shell bearings on the high-compression 440 is a little over-worked- not to the point it fails "early" but to the point that the hi-po big blocks weren't a 200k mile engine like the low-po engines frequently were. And they honestly were never intended to be. But that kind of wear at 50k???? Wowsers.

 

[OVERKILL]

Not surprising in the least. Those of us familiar with the limits of UOA's (thanks to Doug Hillary's excellent and extensive posting on the subject) know that their primary purpose is to monitor oil life and contamination, not as a wear-monitoring tool.

 

[Trav]

No surprise at all. Unless you are looking for fuel or coolant a UOA on a daily driver is as useful as a suitcase with no handle.

 

[JOD]

There are significant limitations w/spectrographic analysis since it only looks for particles of a certain size. Here's a link on PQ Analysis , which gives a more detailed look at what's in the oil.

Also, keep in mind that 100% of particles over a certain size are going to be captured by the oil filter. A UOA is a good tool do help establish OCI length, but that's about it. The wear metals are mostly for entertainment. Sometimes it can help spot a major mechanical function, sometimes not.

 

[tig1]

The acceptable limits for lead is 40-100PPM and copper is 10-50 PPM, so something else is going on here. As Trav and Overk1ll have said, that judgeing wear from a UOA will not tell you the real and measurable metal wear of an engine.

 

[Garak]

A UOA might give you a heads up on wear related issues, but there's no guarantee that a UOA must show wear related issues.

 

[MolaKule]

I guess my question is, what is it about the design of this engine or lack of design that requires a 60 weight oil?

 

[spasm3]

Weren't those engines known for having too soft of a bearing, and they spec'd the 60wt to stave off the problem?

 

[Phishin]

Originally Posted By: MolaKule
I guess my question is, what is it about the design of this engine or lack of design that requires a 60 weight oil?


That's what I was thinking!! How can a high performance engine from a luxury high-end car maker build an engine that would spec 10w60 oil? It's hard to understand.

 

[jaj]

BMW Specs 10w-60 in their engines that run high RPM's - the S62 redlines at 7,000 RPM and the S85 at 8200 or so (might be off a bit but not very far). Ford specs 5w-50 in their 7500 RPM Boss 302 V8. There's a trend here.

Ford's explanation of the high viscosity is not that it's needed when the engine is is at max RPM and working hard, it's that you need that viscosity to ensure there's adequate oil pressure when the engine goes back to idle from running flat out. BMW doesn't explain anything.

 

[JohnAnthony]

Thanks for everyone's contribution and addressing any misconceptions

Originally Posted By: jaj
BMW Specs 10w-60 in their engines that run high RPM's - the S62 redlines at 7,000 RPM and the S85 at 8200 or so (might be off a bit but not very far). Ford specs 5w-50 in their 7500 RPM Boss 302 V8. There's a trend here.

Ford's explanation of the high viscosity is not that it's needed when the engine is is at max RPM and working hard, it's that you need that viscosity to ensure there's adequate oil pressure when the engine goes back to idle from running flat out. BMW doesn't explain anything.


8250RPM for the S85

my opinion is that based on how M cars are advertised the use expected they would require a 60 weight for similar reasons as the ford

over on M5Board
the wear for the S62 has been attributed to the Oil Pan design,
while the S85 is yet to be determined

 

[CSBM5]

Originally Posted By: jaj
BMW Specs 10w-60 in their engines that run high RPM's - the S62 redlines at 7,000 RPM and the S85 at 8200 or so (might be off a bit but not very far). Ford specs 5w-50 in their 7500 RPM Boss 302 V8. There's a trend here.

Ford's explanation of the high viscosity is not that it's needed when the engine is is at max RPM and working hard, it's that you need that viscosity to ensure there's adequate oil pressure when the engine goes back to idle from running flat out. BMW doesn't explain anything.


John, You've been missed on the M5board -- been a few years I guess. Do you have any more detail on what Ford explained? I've wondered about issues like you mentioned, including stuff like people revving engines hard in neutral and also curious how the rod bearing oil film, already under extreme stress at 8300rpm in the S65, looks like during the transient condition when the DCT can shift to the next higher gear in 80ms or less. That has to be an interesting time period to analyze/visualize given the high rate of change of rpms -- the transition from a fully loaded bearing changing to completely unloaded back to fully loaded.

Which makes me wonder further if we would see differences in wear rates on these engines (S85, S65) depending on whether they were SMG/DCT or manual transmission cars. Unfortunately, in field data are unlikely to be reliable since I would suspect SMG/DCT cars are driven harder more often (just because you can, it's so easy, these transmission attract people interested in hammering them, etc) than manual cars..."in general."

Finally, I wonder if someone here can comment on a two part question I posed in the M3post forum in a rod bearing thread populated: two questions, one on non-Newtonian behavior of modern synthetic multi-weight oils

Cheers,
Chuck

 

[440Magnum]

Even with 60-weight oil, its obvious that SOMETHING in the design of those engines missed the mark and the band-aid isn't big enough...

 

[MolaKule]

Originally Posted By: 440Magnum
Even with 60-weight oil, its obvious that SOMETHING in the design of those engines missed the mark and the band-aid isn't big enough...


So does the OM have a maintenance schedule which shows that after every 10th oil change, one replaces rod and main bearings?

I wonder if the bearings are too thick, or are the bearing bolt torques too high, as designed? What are the radial clearances?

From the pictures, it does not appear the bearings are getting too hot.

As far as commenting on another thread on another website, my opinion is you should explain your comment or question here on BITOG and limit any discussions to BITOG.

People are usually busy and don't have time to read external websites, much less all the posts in threads here.

 

[OVERKILL]

Originally Posted By: 440Magnum
Even with 60-weight oil, its obvious that SOMETHING in the design of those engines missed the mark and the band-aid isn't big enough...



*engine

The S62 doesn't appear to be inherently prone to rod bearing failure under most operating conditions. I'm sure there are exceptions, but there are a number of high mileage guys on M5board who, IIRC, just DD their cars (still driving them hard, but no high-G cornering like you'd see on a race track) and have not had to replace their rod bearings.

Also, the S62 only spec's 10w-60 up to 03/00 (everywhere outside of the United States). For 03/00+ the cars were spec'd for BMW LL-01 lubricants (GC 0w-30, BMW 5w-30, M1 0w-40, PU 5w-40....etc) but at some point the US recommendation went back to TWS for these cars, whilst Canada, Germany....etc retained the LL-01 spec

There are ALL KINDS of theories regarding the whole TWS thing in the S62, but nobody has had a failure that can be contributed to using the LL-01 oils AFAIK.

Now, to get back to the track thing and perhaps explain a bit more what JohnAnthony was getting at when he said oil pan design.

The S62 has a semi dry sump setup, at least that's what BMW calls it. Essentially you have an odd shaped "pan" with "kicks" on both the left and right sides that is right at the front of the motor. Oil is drawn from this pan to lubricant the engine (obviously) however, there are solenoids on each side of the pan within these "kick" areas that are activated by the G-forces the car sees during cornering. This redirects the oil flow and the oil is literally sucked down from the outside head on a turn by a scavenging pump to prevent starvation. Or at least that's how it is supposed to work in theory.

My buddy Andrew has a theory regarding the operation of this system and the solenoids failing, resulting in starvation and bearing death. When he bought his car (a 2000) he tested both solenoids and one was dead. Yet there were no codes stored in the ECM for the solenoid's failure. This likely indicates that there's no way for somebody to know that one of the solenoids has died without actually testing them. This is a bit disconcerting if you track your car, because if the system doesn't work as intended it is very likely that you will experience oil starvation and cause bearing damage or worse.

And a few pics of this funky pan setup:

 

[SteveSRT8]

Originally Posted By: 440Magnum
Even with 60-weight oil, its obvious that SOMETHING in the design of those engines missed the mark and the band-aid isn't big enough...


Literally proven, not just accepted as truth.

It amazes me that with the outrageously sophisticated engineering in these cars that they have these issues. I have an acquaintance in Fl with a V10 M5 and he is literally afraid of his car.

Overkill's V8 M5 was one of the cars under consideration when I bought my last new car.
I still love that particular model, VERY few cars have that much luxury AND driver involvement. But I can't say I am sorry I didn't get one!

 

[JohnAnthony]

Originally Posted By: MolaKule

As far as commenting on another thread on another website, my opinion is you should explain your comment or question here on BITOG and limit any discussions to BITOG.

People are usually busy and don't have time to read external websites, much less all the posts in threads here.

the discussion that i was looking for is just this, the link to m3post fills in the accepted reason for premature V10 S85 & V8 S65 engine failures which i did not know when i put up this thread.

for the main discussion the reason for the failures in the V10 & V8 is bearing clearances.
-it's suggested that the clearance were an oversight at BMW
-or that heat cycling has caused the rods to shrink/deform thus reducing the clearances... but i'm skeptic about this one since cycling between 0°C to ?300°C? doesnt seem like enough to deform the rods, especially since it's not a quench, but a gradual cooling

 

[OVERKILL]

Originally Posted By: JohnAnthony
Originally Posted By: MolaKule

As far as commenting on another thread on another website, my opinion is you should explain your comment or question here on BITOG and limit any discussions to BITOG.

People are usually busy and don't have time to read external websites, much less all the posts in threads here.

the discussion that i was looking for is just this, the link to m3post fills in the accepted reason for premature V10 S85 & V8 S65 engine failures which i did not know when i put up this thread.

for the main discussion the reason for the failures in the V10 & V8 is bearing clearances.
-it's suggested that the clearance were an oversight at BMW
-or that heat cycling has caused the rods to shrink/deform thus reducing the clearances... but i'm skeptic about this one since cycling between 0°C to ?300°C? doesnt seem like enough to deform the rods, especially since it's not a quench, but a gradual cooling


Wouldn't that mean that running a THINNER oil would help in this situation then?

 

[JohnAnthony]

Originally Posted By: OVERKILL


Wouldn't that mean that running a THINNER oil would help in this situation then?


it should helps some with the S65 & S85, the vanos may be affected but not to the extent that it causes a vanos failure

while the S62 should probably run on multiple viscosities if you experience cold cranks in 100°F


it both cases owner's basic understanding of oil definitely plays a role in these failures, for example one of the members on m3post understood synthetic oil nomenclature as
10W = 10 weight when cold
&
60 = 60 weight when hot.... according to him synthetic oil "Thickened" as it warmed up