BMW's Oil Viscosity changes. (quick question) - Page 2 - BMW M5 Forum and M6 Forums
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post #11 of 100 Old 15th December 2016, 06:19 AM
Sailor24
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Any idiot working for BMW should have told him that they changed their minds and that they now only recommend 10w60 for the M5.

From a document I have posted many times

BMW Recommended/Approved synthetic oils doc. January 2008, Version 1.0

"The following is the only recommended and approved synthetic oil for BMW M
(Motorsport) vehicles in the US market with gasoline engines, at the present time.
BMW Long-life rating LL-01 Synthetic Oils for BMW M vehicles
equipped with S54, S62, S65 or S85 engines
Castrol TWS Motorsport SAE 10W-60 Synthetic Engine Oil, or
Castrol Formula RS SAE 10W-60 Synthetic Engine Oil
(BMW part number 07 51 0 009 420)
If Castrol High Performance Synthetic Oil is not available and you need to add oil
between oil changes, only use synthetic oils with the following specifications for M
vehicles:
Viscosity – preferred SAE 10W-60
Alternative – SAE 10W-40, SAE 5W-50 or SAE 10W-50
Use only oils with an API rating of SJ/CF, SK/CF or higher"
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post #12 of 100 Old 15th December 2016, 08:31 AM
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and now, for something completely different:

http://test.resource.bmwusa.com/Pdf_...12c1eea2c.arox

I believe if one reads both pages any and all discussions will stop. Merry Christmas all

Thanks Sailor, I just posted the link to your copied and pasted posted numerous times document. Thanks again

Last edited by Thumper600; 15th December 2016 at 08:33 AM.
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post #13 of 100 Old 15th December 2016, 01:50 PM
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Quote:
Originally Posted by ard View Post
Are people actually discussing and comparing oils based on the labeled viscosity range?!?!

the "0"...the '5'..the '30'????

Pretty funny.

I would never use oil thinner than the BMW HiPo 5w30 (which was close to a 5w40)... I run 10-60

I dont know the specs on BMWs new 0-30, but OP is wise to question BMW parts clerks.
The average 0w-30 is no thinner than the average 5w-30 (or 10w-30 or straight 30) at operating temperature.

The labeled viscosity range is the correct way to compare oil viscosity-- it represents a range of thicknesses, when new, that the oil falls within. BMW's former 5w-30 is a thicker 30, but still in the 30 range. BMW's former 10w-60 was a thinner 60, but still in the 60 range (thought it becomes a 50 in the fist couple hundred miles, where it holds steady for a long time).

I don't think you're going to do any significant harm running a 10w-60. If I were to track the M5, it's what I'd put into it. But, when BMW specs oil, it has to be for all possible use cases of the car-- in the M5's case, that has to include tracking on a hot day. For those of us not tracking the M5, a 10w-60 just results in less power, less fuel economy, and more wear. And no, no matter how reckless/suicidal/stupid you are, you can't pull track level stresses on the car through aggressive street driving. People never believe that until they've actually tracked a car, but that's just a fact.

Last edited by Obioban; 15th December 2016 at 04:21 PM.
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post #14 of 100 Old 15th December 2016, 01:50 PM
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post #15 of 100 Old 15th December 2016, 02:30 PM
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Quote:
Originally Posted by seabass23 View Post
I stand by my original wording. At extreme temperatures (ABOVE normal operating), the 0W-30 provides BETTER protection. If you graphed viscosity vs. temperature on a log scale, you'd create two straight lines. Both lines would pass through the same viscosity at operating temperature but the cold start viscosity is lower for the 0W-30, therefore creating a flatter sloped line. As a result, your viscosity at extreme temperatures is HIGHER with 0W-30 than it is with 5W-30.
I think you're a bit off.

A better indicator of what you're looking for is viscosity index. The higher the VI, the less the viscosity changes with temp (which would be a shallower ramp, not a steeper one). That means it thickens less at low temps, thins out less at high temps. Typically a 0w-30 will have a higher VI than a 5w-30.
Caveats:
1. if the 5w-30 is made with much thicker base stocks than the 0w-30, it might still be thicker at all the hot temps it'll actually see
2. there's more than one way to get a high VI, and some methods leave the oil with less shear stability. so, in the hottest parts of the engine, the shear forces might make the 0w-30 thinner than its VI would suggest at that temp

so, if you're comparing Mobil 1 5w-30 to Castrol Edge 0w-30 SPT, the 0w-30 will likely be thicker when really hot because it'll hold its viscosity better
but if you're comparing BMW 5w-30 to Mobil 1 AFE 0w-30, the 5w-30 will probably be thicker when hot. One way to figure this out would be to look at VI and HTHS viscosity.
if both are high, that's one hell of an oil when hot
high VI + low HTHS = really not shear stable
low VI + high HTHS = likely suitable, though might be thicker than preferable when cold
low VI + low HTHS = terrible
(this is all assuming you're comparing oils within a given viscosity grade, e.g. xw-30)

Last edited by Obioban; 15th December 2016 at 02:32 PM.
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post #16 of 100 Old 15th December 2016, 04:11 PM
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Quote:
Originally Posted by Obioban View Post
I think you're a bit off.

A better indicator of what you're looking for is viscosity index. The higher the VI, the less the viscosity changes with temp (which would be a shallower ramp, not a steeper one). That means it thickens less at low temps, thins out less at high temps. Typically a 0w-30 will have a higher VI than a 5w-30.
Caveats:
1. if the 5w-30 is made with much thicker base stocks than the 0w-30, it might still be thicker at all the hot temps it'll actually see
2. there's more than one way to get a high VI, and some methods leave the oil with less shear stability. so, in the hottest parts of the engine, the shear forces might make the 0w-30 thinner than its VI would suggest at that temp

so, if you're comparing Mobil 1 5w-30 to Castrol Edge 0w-30 SPT, the 0w-30 will likely be thicker when really hot because it'll hold its viscosity better
but if you're comparing BMW 5w-30 to Mobil 1 AFE 0w-30, the 5w-30 will probably be thicker when hot. One way to figure this out would be to look at VI and HTHS viscosity.
if both are high, that's one hell of an oil when hot
high VI + low HTHS = really not shear stable
low VI + high HTHS = likely suitable, though might be thicker than preferable when cold
low VI + low HTHS = terrible
(this is all assuming you're comparing oils within a given viscosity grade, e.g. xw-30)
This oil thread has broken down just like they all seem to do. Let's all scroll back to the original post where a fellow user asked a pretty basic question about comparing two different bottles of oil.

Although it was implied by the photo, he didn't actually even tell us what car it was going in to!
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post #17 of 100 Old 15th December 2016, 04:17 PM
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Quote:
Originally Posted by seabass23 View Post
This oil thread has broken down just like they all seem to do. Let's all scroll back to the original post where a fellow user asked a pretty basic question about comparing two different bottles of oil.

Although it was implied by the photo, he didn't actually even tell us what car it was going in to!
lol, my post was an example of a thread breaking down? I think not. It was presenting factual information about the question that was asked by the OP in the first post thread of the thread.

Last edited by Obioban; 15th December 2016 at 04:23 PM.
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post #18 of 100 Old 15th December 2016, 04:32 PM
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post #19 of 100 Old 15th December 2016, 05:44 PM
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Quote:
Originally Posted by Obioban View Post
lol, my post was an example of a thread breaking down? I think not. It was presenting factual information about the question that was asked by the OP in the first post thread of the thread.
All I meant was that the OP presented his question in very simple terms, implying that he was looking for an answer that was also presented in simple terms.
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post #20 of 100 Old 15th December 2016, 05:45 PM Thread Starter
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Quote:
Originally Posted by seabass23 View Post
Although it was implied by the photo, he didn't actually even tell us what car it was going in to!

Even with the photo, I just assumed you guys knew I was talking about my truck


thank you all for the lively discussion about this.

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