why does bmw require 10w60 ?

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I know where you're coming from on that, Caterham, and I agree that it is better to solve the root cause of a problem. But an oil pickup problem is more expensive to solve than just pouring in a thicker oil. Solving oil drainage and scavenging, and crankcase venting and breathing problems is more successfully accomplished by OEM's and technically capable engine specialists. It takes design, instrumentation, and testing capabilities that are financially beyond the reach of home hobbyists. I've played that scene as a development engineer with 3 separate engine manufacturers and with my own Corvette at home. It takes carefully planned tests with a lot of instrumentation to even identify what is occurring in the engine that causes oil starvation, and then design and manufacturing assets to implement solutions once the problem is understood. The home hobbyist is more or less just feeling his way through the dark.

My experience with the Corvette is a case in point: After I saw that the engine was losing oil pressure in Turn 6 at Watkins Glen, I went on a search for a better oil system. I ended up sourcing a fabricated 7-quart pan with an expanded metal windage tray, side wings, and trap door baffles that were supposed to keep the oil close to the pickup. With the pan, a new high-volume pump was supplied that had a small-diameter pickup brazed on. OK, I thought this was the hot setup, and I installed it over one winter and took the car to the Glen in the spring. After a few laps, I saw that the engine was still losing oil pressure in Turn 6, and the oil temperature was still maxing out at 280F+. From the data I had available to me, I could not see any improvement, but I kept the system on the car for a couple of years. Eventually, I went back to the OE pan and pump setup because the fancy pan leaked and made working on the engine more difficult.
 
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A_Harman: thank you for that post, very interesting and a good read! I am now second guessing buying a higher capacity baffled oil pan for my 328 (never had any real starvation issues, but the supercharger shares oil supply with engine), but I still figure there would be an upside to an extra 2-3qts of oil in the car cooling the engine/SC with assistance from the aftermarket oil cooler (fabbed an aftermarket 335i oil cooler to fit). I was worried about the OE pump being able to keep up though and I do not feel as comfortable changing stuff like that which is so instrumental in keeping the engine from turning into a very expensive grenade...
 
A_Harman I hear ya and I too know how frustrating it can be trying to remedy an oil starvation problem with a wet sump set up.

I just don't want anyone reading this thread to assume for a second that running a thicker oil than would otherwise be necessary is a remedy in anyway to deal with an oil starvation problem. It often exacerbates the issue by creating other problems. Personally I've found if we're talking about temporary fixes, overfillling the crankcase with the appropriate oil viscosity is the preferred approach.

Getting back on topic, oil starvation of course is not the reason why BMW spec's a 10W-60 for it's M series engines. The reason they still do is the possibilty of very high oil temp's when driven very hard and the resulting high oil consumption that often occompanies such driving conditions.
 
Originally Posted By: CATERHAM
Originally Posted By: 45ACP
Originally Posted By: dailydriver
Originally Posted By: nleksan
A_Harman said:
nleksan said:
I think we just disproved Dr Haas's theories in this post.
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fwiw, i would totally have been thinking 0W-40 was ok with a car like that.

A 0W-40 like M1's is perfectly fine if the oil temp's are contained. It is a very common oil choice for E36 and E46 Bimmers at the track, M3 or otherwise.
Due to it's high 185 VI it's a very practical oil at most track day events since most drivers don't have the patience to wait
for the oil to come fully up to temperature before extracting full performance from their cars. And since most track sessions are no longer than 20 minutes high oil temp's are not often a problem even on a hot day.

Ali Haas' theories have not been disproven in the slightest.
Driving high performance cars on the street simply cannot generate the oil temp's that you can on the track.
He never sees oil temp's in excess of 100C in any of his cars and the Enzo max's out at a rather tepid 82C.


yes they have, slightly, in one respect..... and that would be: can you explain to these people how Dr Haas's (he is in the minority in income, driving style, choice of cars, to 99% of America, he says he uses his cars for no more than 10-15 minutes at a time) motor oils that he says are 0W-20 and 0W-30 are actually more like mid-30 for the 0W-20 and low-40 for the 30 if going by HTHS and not the labeling of the oil?

OP, in post 1, commented on very high oil temps with one oil and not another. I think that is why BMW spec'd the thick oil in the first place! But back to Dr Haas, did you yourself not say that they oils he calls 0-20 and 0W-30 are in fact that "in name only" and are what the general public that reads this site would actually be calling closer to a 30 and 40 weight, respectively?

Most people with an Enzo would be using it -slightly- hard and maybe getting the oil up to "normal" temp. Dr Haas has a driving style he himself says is less common. So, being so quick to say EVERYONE can do what he says.. thats the run with me. It gets back to "As thin as possible but as thick as necessary" but you yourself said that Dr Ali E haas "exaggerates."

Right?

That would sure clear up a lot. it seems to be a sticking point.

As to the M, you are right i think the manual specifies "0W-40, 5W-50, or 10W-60 depending on condition." You have also said that Redline 5W-30 is a good choice. Well, why not Redline 0W-30 then? I dont fully understand why the "0" would not be ok, unless the 5W-30 is actually thicker than the 0 in that line of oil. Would you really put 5W-30 Redline in that car and then take it to the track for a DAY on the track? This isnt a rub on you specifically. Just curious.

A lot would choose the 10W-60 for that same application.. I know you said Redline 5W-50 is thicker than it but some people run that too...

I have never taken a car to a track but i have pushed my BMW hard and i used to put either 10W-40 or 20W-50 in mine to handle the temperature. 100 degree Summer says tend to always have the best weather to push the car. 110, 120MPH... trackLIKE sure but then i drove for hours that day as well.. all day, actually.. turned the car off at 8PM or later was driving since early morning.. HOT day. If i had the car again i would choose from 0W-40, 5W-40, 5W-50, or 10W-60 (or the 0W-40 or 5W-50 Redline.) Unless i can be convinced....
 
Also.. the Enzo has a 5W-60 available. FF in Enzo, i heard! 5W-60 not 10W-60. Castrol RS? Im not sure the make.. but perhaps that could work here too.
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Ford GT FFs 5W-50
Mercedes-McLaren SLR and new SLS FFs 5W-50
Veyron FFs 10?W-60

So far thats all i got...
 
Originally Posted By: 45ACP
As to the M, you are right i think the manual specifies "0W-40, 5W-50, or 10W-60 depending on condition." You have also said that Redline 5W-30 is a good choice. Well, why not Redline 0W-30 then? I dont fully understand why the "0" would not be ok, unless the 5W-30 is actually thicker than the 0 in that line of oil. Would you really put 5W-30 Redline in that car and then take it to the track for a DAY on the track? This isnt a rub on you specifically. Just curious.

A lot would choose the 10W-60 for that same application.. I know you said Redline 5W-50 is thicker than it but some people run that too...



Because the HTHS of Redline 0w30 is 3.2, and 5w30 is 3.8. To meet ACEA A3/B3/B4, an oil has to have HTHS of at least 3.5. To get a Redline 0wXX oil that meets HTHS for ACEA A3/B3/B4, you would have to go up to 0w40, which has 4.0. Many people say that Redline oils perform like an oil that is a grade heavier. This is because they have very high HTHS's in relation to their API-rated kinematic viscosities. I don't think this applies to Redline's 0wXX line. They have a ratio of HTHS to KV that is more like everybody else's oils.

Here are some comparative numbers between the HTHS's of Redline and other oils:
RL 5w20 = 3.3
M1 5w30 = 3.1

RL 5w30 = 3.8
M1 0w40 = 3.8

RL 5w40 = 4.6
M1 5w50 = 4.4

RL 5w50 = 5.9
Does anybody out there know what the HTHS of Castrol 10w60 is? I'd bet it isn't as high as RL's 5w50.
 
45ACP, I agree with much of what you've said.
Dr. Haas doesn't fully understand the relationship between HTHSV, kinematic viscosity and the SAE grading system so there is some inconsistency when he gets into the specifics of appling what he preaches.
But I do philosophically agree with Ali Haas when one is talking about oil viscosity in general terms and he does recognize that oil pressure is the bottom line in selecting the correct viscosity for any application.
 
Originally Posted By: CATERHAM
45ACP, I agree with much of what you've said.
Dr. Haas doesn't fully understand the relationship between HTHSV, kinematic viscosity and the SAE grading system so there is some inconsistency when he gets into the specifics of applying what he preaches.
But I do philosophically agree with Ali Haas when one is talking about oil viscosity in general terms and he does recognize that oil pressure is the bottom line in selecting the correct viscosity for any application.


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I agree with you. I can grasp, through using thinner oils in my cars that they do perform better. And once i get things out of the way like "they recommend heavier grades for long periods of operation" and things like that, i agree with a lot of what you say. Im not sure i would ever mix, but Redline is a favorite and i agree i would likely seek it.

Also i believe that A_Harman has made the most relevant post and observation about the Redline and the HTHS of 0W and 5W grades, and how to relate it to the minimum HTHS of 3.5 that Porsche and BMW specify. Im c/ping both of those posts. Thank you, CATERHAM and A_Harman. I used to put heavier oils in the BMW now im reading and i can see the point of the BMW guys that say a good 5W-50 may negate the need for TWS 10W-60. Its so much information! I appreciate this resource. I am happy i could point that out, as i feel it confuses a lot of people and causes some of the things Dr Haas says to be dismissed where in actuality they shouldnt be. He seems on-point about most. So do you! Thank you. Thank you both!

btw my car died so i am shopping for another. I dont see it happening anytime soon. Im in DM's GMC so im keeping an open mind to ALL potential replacement vehicles. Could very well be an old 525i from 1992, first year of the new style. Should i go that route, ill likely get the RL 5W-30 based on what i have read (performs like M1 0W-40) and call it a day.

If you told someone "The Redline 5W-30 performs almost exactly if not exactly like the Mobil 1 0W-40" then people would not be all up in arms over someone suggesting a 5W-30 for their car that the manufacturer says to use 10W-60 in, and im quite sure the Redline could withstand a day on the track in that grade. True? Or would you move up to the 40weight Redline oil, the 0W-40..? (as to OP's question/observation.) Could the 5W-30 remain in at all times, especially if its a light track day use? This could be eye-opening information..

What oil for ~30 minutes - "three hours" on the track and what oil from dusk till dawn on the track? Thanks!
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Also the BMW would be my DD....

Quote:

RL 5w50 = 5.9
Does anybody out there know what the HTHS of Castrol 10w60 is? I'd bet it isn't as high as RL's 5w50.


I do not know the spec of TWS 10W-60. Apparently it flows extremely well for its 10W designation, much the same way Mobile 1's 15W-50 is actually a 10W as put forth some time ago. And these are good things.

I agree with all you have posted.

d00df00d had a very very good post on Page 1 describing very well why people use TWS 10W-60 and it made me want to seriously consider it if i ever got this particular M, which is a ways off for me. For the more "normal" BMWs, i think the 10W-60 is overkill and i can see the logic behind RL 5W-30 now. Question is RE: the same RL 5W-30 for the TWS 10W-60 app...
 
Originally Posted By: A_Harman
Originally Posted By: 45ACP


Does anybody out there know what the HTHS of Castrol 10w60 is? I'd bet it isn't as high as RL's 5w50.

You're right it isn't. IIRC TWS 10W-60 has a HTHSV of 5.4cP and 172 VI. And the other factory spec' 10W-60, Shell Helix Ultra has a HTHSV of 5.42cP and a 180 VI. The Shell oil is also BMW 'M' approved. Both these oils are known to shear a lot in service, at least 25% into the 40wt range. I suspect that happens rather quickly and then stabilizes. Obviously the manufacturers that spec' these oils don't have a problem with the oil shear characteristics and if they were labelled as 10W-40 oils instead they would still be the recommended oils.

As I have said for a long time now the SAE grade on the bottle has more to do with marketing than anything else.

RL 5W-50 has a HTHSV of 5.9 and 185 VI. Since all RL oils are very shear stable, this oil would clearly be too heavy for use in anything for which the afore mentioned 10W-60 would be spec'd.
RL's 5W-40 or 10W-40 would likely provide similar operational viscosity characteristic to the factory 10W-60's or even possibly RL's 0W-40. As many know, I'm not a fan of RL's 5W-40 (contains no moly) for gas engines nor their 10W-40 for it's lowish VI. So I would go with RL 0W-40 and If you need something heavier simply blend in some RL 5W-50 to suit. This way you'll retain a 190+ VI and minimize the cold start issues of running a heavy oil.
 
Originally Posted By: CATERHAM
And as I said, g-load should not be a factor in an engine's viscosity choice. If you have an oil pick-up problem, solve the pick-up problem.



^^^OF COURSE, agreed!!

I was only implying the viscosity choice as an inappropriate/temporary 'band-aid' ONLY (as A.Harman has) for very high temp, in turn, very high g-loading apps, no matter how wrong that may be, as relevant to this discussion.
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I also fully agree with you on RL's 5W-40 being undisirable for it's reduced add pack vs. their other products.
 
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