BMW recommends 20w50 weight for dino oil.

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591
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Pittsburgh PA
In my 94 540i. I ran M1 15w50 in it this summer but I'm thinking that maybe a 5w30, 10w30, 10w40 synthetic may be a better choice. 285hp V8. The manual states 20w50 dino oil year round here in PA but I think that's pretty thick for winter time. I've got some Amsoil 10w40 and 20w50 on hand.
 
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5,785
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Dixie
I'd run the 10w-40 unless you are having oil consumption problems ....I've had excellent results with the Series 2000, 20w-50 in older 3 and 5 series BMW engines, but I think the newer ones will do better on 5w-40 or 10w-40. BMW was supplying both 5w-30 and 5w-40 factory fill oils for this application that met the ACEA A3/B3 specifications. The specs for the 5w-30 are posted on the Maxima.org oil spread sheet.
 
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5,785
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Dixie
The engine will run significantly cooler with a 10w-40, PAO/Ester synthetic than it will with a 20w-50, petroleum racing oil. So the oil will not thin out as much and oil pressure will be very comparable. You get much better oil flow during startup/warmup with the 10w-40 synthetic, so it's a win/win situation. You will also pick up 2%-3% in fuel efficiency .... I have been taking this approach with numerous engines over the past 17 years with outstanding results. You have to keep in mind that engine manufacturers oil recommendations are made with the assumption that you are going to run the cheapest, lowest quality oil you can find. The same situation exists with two cycle engines.... In this case, they normally recommend a lean oil/fuel ratio of say 50:1 if you run the manufacturers oil and a richer, 25:1 mix if you run somebody elses oil. They don't know what crummy off brand oil you are going to buy, so they take the CYA approach [Wink] The key to deviating from manufacturers lube recommendations is having a good fundamental understanding of tribology ....
 
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47,644
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Duvall WA - Pacific NW USA
Patman wrote:
quote:
The 20 in 20w50 doesn't mean it will behave like a 20wt when it's cold. That's what a lot of people think, but the 20 is just an arbitrary number assigned to the oil that corresponds to a certain cold cranking value.
I knowed that. In general I meant it will be like a thixotropic goo when cold....in particular I meant the 20W synthetic will have a much lower pumpability temp than the dino 20W....
 
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2,095
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IL
quote:
Originally posted by TooSlick: ....I've had excellent results with the Series 2000, 20w-50 in older 3 and 5 series BMW engines, ...
Wasn't it you that told me the M1 15w50 I used was too thick?? [Big Grin] Have you seen any analysis with synthetic 10w30 in those motors? I am thinking of RL 10w30 next.
 
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5,785
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Dixie
Jason, I specifically said I thought 15w-50 was too thick to use in the winter in Chicago. I'm talking about running 20w-50 in Alabama, where a cold day is anything < 50F. [Smile] I still think you are better off with the Redline 10w-40 in cold weather, although you could run their 15w-50 in the summertime ....
 

1maniac

Thread starter
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591
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Pittsburgh PA
The previous owner ran only Castrol GTX 20w50 for the last 8 years / 65k miles. This thing doesn't use a drop between changes and that's been on M1 15w50 since I got it. So I'm correct in thinking that Synthetic 10w40 is better suited for winter use?
 
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47,644
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Duvall WA - Pacific NW USA
If you are sticking with 20W-50 - I'd stay with synthetic. Not sure how cold it gets there, but dino 20W-50 is mighty thick when cold....(sure doesn't look like a 20W!!) I have been using the Series 2000 20W-50 in my 1985 Volvo 245Ti for 2 years with great sucess (10K oil chnage intervals). See the analysis forum here.
 
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349
Location
Quebec, Canada
Apart from what's been suggested already, how about a 5W50? Unfortunately, we do not have that many brand choices around here for that weight. Regards, Oz
 
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233
Location
Midwest
The book specifically says 20w-50, so use it. Unlike US cars that all have 5w-30 for fuel economy, BMW obviously wants a heavy oil for engine longevity and says 20w-50 year round. I would definately not go with a 5w-30. Even my VW VR6 specifically says not to use 5w-30. The european car makers are looking for what best for the car not the gas mileage.
 

Patman

Staff member
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21,989
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Oakville, Ontario
quote:
Originally posted by Pablo: If you are sticking with 20W-50 - I'd stay with synthetic. Not sure how cold it gets there, but dino 20W-50 is mighty thick when cold....(sure doesn't look like a 20W!!)
And it shouldn't. The 20 in 20w50 doesn't mean it will behave like a 20wt when it's cold. That's what a lot of people think, but the 20 is just an arbitrary number assigned to the oil that corresponds to a certain cold cranking value.
 
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223
Location
Long Island NY
I used Castrol 20-50 dino in a '80 Honda Civic for 178k troublefree miles here in NY. The engine was in great shape when I sold it BUT cold starts when it was below 32 really let you know how thick the oil was. The current -zero- weight Mobil-1 synthetic oils make it seem like the car has been pre-heated as it turns over so easily even when it's 20 degrees outside.
 
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5,785
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Dixie
1maniac, Yes, a 10w-40 will give you an advantage of about 10F in terms of cold pumping characteristics, compared to a 20w-50. I'd run the 20w-50 during the warmer months of the year, when the expected temps for the next oil change interval are above freezing .... Mark, People do all sorts of crazy things, but running a 20w-50 - even a synthetic - in subfreezing temps doesn't fall under what I would call "best practices". Who can say if you would not have gotten even better results if you had used a thinner oil in the wintertime? You certainly would have gotten better performance and fuel efficiency by using a 5w-30 or 10w-30 in the wintertime. JUst something to consider .... TooSlick
 

Patman

Staff member
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Oakville, Ontario
I know there are a few people here that are gonna disagree with me, but I can't see a 20w50 benefitting any engine even in the hottest months. Only a race engine with very loose clearances and a high volume oil pump would need an oil that thick, certainly not a passenger car though.
 
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47,644
Location
Duvall WA - Pacific NW USA
Well I am on my second 10K run S2K 20W-50....and I still agree with you: 20W-50 isn't for street vehicles - although my reason wasn't necessarily "engine protection", I seem to be acheiving it....I started out, "just wanting to try all my products" - and got hooked...mainly low volatility, viscosity retention...my car uses essentially no oil, now. Frankly I was really paranoid (rightly so) about the turbo bearings during cold starts....but study the numbers. The stuff still pumps pretty darn cold. We sometimes might go to +20 or 25°F here (with the very ocaisional blast into the teens). I'm gonna try the Diesel 5W-30 next and even do an AutoRx first...because I haven't used that personally yet......
 
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191
Location
KY
quote:
Originally posted by dagmando: Even my VW VR6 specifically says not to use 5w-30. The european car makers are looking for what best for the car not the gas mileage.
My 1999.5 Jetta VR6's manual says that 5w-40 is preferred, but 5w-30 is "acceptable." What year is yours?
 
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223
Location
Long Island NY
I would not go back to 20-50 these days, but you can't argue with the numbers. When I sold the Honda @ 178K miles, I checked the engine on the day of sale out of my own curiosity. Compression was TWO PSI between the lowest and highest cylinders! This was only one PSI cylinder to cylinder. Using a mechanical oil pressure gauge indicated 40 PSI at 2500 RPM. Oil consumption was minor between oil changes (every 6 months, irrespective of mileage). Between this experience and my engine building and racing in the 70's I have been somewhat suspicious of the lighter oils as far as maximum engine life is concerned. I weakened somewhat and used 5-30 in a 91 Honda Civic that I kept for "only" 110K miles. At the time of sale it was burning more oil than I was comfortable with. This is why I am now using 0-40 M-1. If I went back to dino I suspect I would use 10-40. In any case, with all of the talk about SAE grade choices I see that you really need to look at the temp-vis charts to see the story about how different oils flow over the actual temp range and how synthetics differ from the same grade conventional oil. Hope I'm not getting to wordy here......
 

Patman

Staff member
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21,989
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Oakville, Ontario
What I would really like to see is someone do a test of all the different viscosities in the same engine, to see if the oil analysis results were drastically different.
 
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951
Location
Loveland, Colorado
1maniac, I'm not a real big fan of what manuals specify any more. I used to be, but changed my mind when I discovered that my Euro car was getting heavier oil everywhere but here in the US. From what I understand, several German car manufacturers are now spec'ing xW-60 wt oils for their machinery. Europe has just as much temperature variation as the US, but more costly resources. To me, this says volumes. I've never owned a BMW, but keeping in mind that most US manuals will spec a thinner oil than their non-US counterpart, I think the fact that your manual DOES say 20W-50 means something. My guess is, for that engine, BMW is more concerned about the 50-end than they are the 20W-end. If it were my car, I'd continue to use what you're using right now: M1 15W-50. It's advertised as having more anti-wear additives than the other M1s, & it's going to do its job well outside of any extremes you'll see. Since you've got the Amsoil on hand, I'm sure the 20W-50 will perform at least as well as the M1 15W-50. I'd save the 10W-40 for another engine. No, I don't think you'd have ANY problems running it, I'm just saying if it were my car... For reference, I'm running M1 15W-50 in a weakling 125hp 4cyl in CO, & I haven't had any cold engine problems yet (down to 15*F so far this year!).
 
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