# mobile 1 10w-40?



## rockbottom8 (Jul 27, 2005)

*mobile 1 5w-30?*

I rmemeber reading the e90 manual and went and bought some mobil 1 synthetic 5w-30 oil just to have to top off every once in a while. Is this a recommended brand. On the engine it says castrol. Wonder if it's just so people buy castrol...lol...btw it also takes 5w-40. What is the difference and which one is better.


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## X3-terrestrial (Aug 27, 2008)

I trust both, Mobil1 meets BMW specifications and I use 0w 40 on both cars. I havent been able to find Castrol on that weight...


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## benjamin_liu (Aug 22, 2008)

5w-40 is better. it can let the engine run well in higher temp.


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## SkyDog (Aug 1, 2007)

If you do a search, you'll find LOTS of threads on motor oil.

In a nutshell... When talking about multi-grade oils, the number, marked by a W (for winter), is a cold rating. Lower numbers are usable at lower temperatures. A 0W oil is tested at -35°C, a 5W at -30°C and a 10W is tested at -25°C. The second number is the viscosity at operating temperature, measured at 100°C. So different weights aren't really better than one another -- just better for different climates. Since you're in L.A., pretty much any "normal" grade ought to work for you, at least in theory. You won't see too many subzero temperatures!

If the approved oils are the same for your E90 and my E46, the only Mobil 1 oil that's BMW-approved (LL-01) is 0W-40. Castrol's "European Formula" (0W-30?, made in Germany) meets the spec, but many other Castrol oils do not. And believe it or not, the OEM BMW/Castrol oil is actually priced pretty competitively at a lot of dealers, so depending on what's available at your local stores, it might be easiest to stick with the OEM stuff.

Hopefully this is all a moot point... You really shouldn't be burning enough oil between changes to need to add any.


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## rockbottom8 (Jul 27, 2005)

SkyDog said:


> If you do a search, you'll find LOTS of threads on motor oil.
> 
> In a nutshell... When talking about multi-grade oils, the number, marked by a W (for winter), is a cold rating. Lower numbers are usable at lower temperatures. A 0W oil is tested at -35°C, a 5W at -30°C and a 10W is tested at -25°C. The second number is the viscosity at operating temperature, measured at 100°C. So different weights aren't really better than one another -- just better for different climates. Since you're in L.A., pretty much any "normal" grade ought to work for you, at least in theory. You won't see too many subzero temperatures!
> 
> ...


Yep! very helpful! Yeah i even called my dealer and he said 5w-30 is fine for toping off....


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