[AWSAWS]

With a tuned 335i often running 100HP more than standard, what grade of oil would you use? a 40 instead of a 30?

What are people's favorites?

[mojobmw_e90]

I run Mobil 1 5w40 turbo diesel oil. Google it and you will see. It's been about 20k now.. I have no ticking noise from engine as other 335 do, and car has 86k on it.

[djgandy]

If I was pushing the car hard a lot and its running 120-130 all the time, I'd run a 40. If you have enough cooling to keep temps under 110 a 30 is fine.

If you want to get really anal, read the actual viscosity figures. Youll probably find a 30 is more like a 32 and a 40 is more like a 38, so the difference isn't that great.

[djgandy]

The tables are here - http://www.kewengineering.co.uk/Auto..._explained.htm

A 30 must have cSt @100C between 9.3-12.5. a 40 must be 12.5-16.3. So take this Castrol spec for
example...

http://msdspds.castrol.com/bpglis/FusionPDS.nsf/Files/4ABA633F17A143FD80257AA90053665B/$File/EDGE%20Professional%20European%20PDS_July_2012.pdf

0W-40 A3 = 13.5
5W-30 OE = 12.1

The 30 is a thick 30, and the 40 is a thin 40. The 40 is not that much thicker at all

All data sheets are available here http://msdspds.castrol.com/msdspds/m...edmb=No&cols=0

I think a 40 will be a bit better at high temps. I think the HTHS value is probably the most important, as the oil in the N54 is prone to shearing.

[AWSAWS]

5W40 it will be then guys. My temp is often just a little below 120.

Thanks

[djgandy]

Yeah the 40's aren't that much thicker than the 30's. It won't do any harm.

bobistheoilguy is the forum you want for oil discussions. Beware though, its like detailing world. Some people get a little too carried away.

[AWSAWS]

Originally Posted by djgandy

Yeah the 40's aren't that much thicker than the 30's. It won't do any harm.

bobistheoilguy is the forum you want for oil discussions. Beware though, its like detailing world. Some people get a little too carried away.

Yes I've read enough to realise that. So long as the oil protects the engine as well as can be expected, I'm happy.