Originally Posted By: Pesca
Originally Posted By: CATERHAM
Or since your BMW is no longer under warranty, if you want to maximize your cold start performance just go with a synthetic 5W-30 like PP or even M1 0W-30. Yes these oils are also a bit lighter at operating temp's but they're still more than heavy enough.
That is a discussion I don't have a conclusion yet on it:
I have plenty of PP 5w-30 and Synpower 5w-30 left in my garage to use, so it would be nice to use them, even on shorter intervals of course, since they are not as stud as the LL-01 oils.
I am partisan of "as light as possible, as heavy as needed"... or something along those lines, especially since I am not under warranty anymore.
My problem for the BMW lies on the HTHS minimal value that BMW requires: Is it for the longer interval or is it related to the design of the engine (tighter tolerances of the cams, etc...)?
If this is for the longer interval, I don't mind use a lighter with lower than 3.5 HTHS oil and change the oil earlier.
If this is a design requirement, I would still continue to use a LL-01 oil.
In doubt, I will take the safest way of course.
As you can see in the first UOA of this car
Dealer Castrol 5w30, 2009 BMW 328iXdrive, 14.621km , cooper level is high and I don't want to make it worse by choosing an improper oil.
I still have about a year left to decide, but I am not sure I will find an answer to my question until then...
PS: BTW, the car is noticeably smoother with GC at all temps, and this is not just in my head as I am not the one who notices this type of things usually.
Hey, I've got you thinking which is good!
Bimmers tend to run lower maximum operating temp's in the winter than they do in the summer which means your operational viscosity is higher on the same oil. BMW spec's a 3.5cP oil so if you do take you car to the track in the summer you'll have that extra viscosity reserve when you're oil temp's are higher than what they normally reach are just driving on the street.
I have found that a 3.0-3.1cP oil is more than heavy enough for even the most demanding street driving conditions on the hottest summer days.
That's why I have no reservations suggesting a lighter 30 grade oil like PP or Synpower for winter use even though you don't have oil gauges to determine for yourself that the oil is not too light yourself.
As you likely can guess, there are probably millions of BMWs and Merc's operating on a lighter than spec' 5W-30 oil in NA once out of warranty.