It's not like this issue has ever been posted before. Here is the link:

http://www.xoutpost.com/x5-e53-forum/...scosity-2.html

Here is the summary:

I'm going to chime in here as a long time oil enthusiest that has spent way to much time on the subject. If you really want to get into it, go spend some time on bobistheoilguy.com and you will get a whole plethera of knowledge.

What to look for in a BMW oil:

1) BMW has its own oil specs. They are BMW Long Life (LL). There have been three standards LL-98, LL-01, and LL-04. BMW LL-98 allows for Group III hydrocracked oils, but LL-01 is stricter and only allows for Group IV or Group V based oils. LL-04 is very new, designed for primarly diesels in Europe and no oils sold in the US actually are LL-04 approved (Amsoil doesn't count as they claim their oil meets the standard, but it isn't approved).

2) The proper oil for all climates is an oil that meets BMW LL-01 or better. There are only a couple of oils that actually meet this spec widely available in the US. Mobil 1 0w-40 and Valvoline 5w-40 Syntec.

3) All BMW Long Life oils are ACEA A3 oils. An ACEA A3 oil means that it has a high temp high shear (HTHS @ 150c) of more than 3.5. Note that A3 is mutually exclusive of ACEA A1 & A5. A1 & A5 oils have an HTHS of less than 3.5. A5 is simply a newer and stricter standard of A1, so if an oil is A5 rated than it is also A1 rated. NOTE NOT ALL A3 OILS ARE BMW LL OILS, ONLY THOSE SPECIFICALLY LABLED AS SUCH.

4) Note that Mobil 1 30 weight oils are not A3 or LL approved. So the next question that will be asked is why does BMW USA recommend them? It is because they never have updated their recomendation from the 90's when Mobil 1 was available in the US in either 30 or 50 weight. There was no 0w-40 then. THE ONLY MOBIL 1 OIL THAT IS BMW LL APPROVED IS THE 0W-40.

5) Don't get to hung up on weight. 30 weight oil runs from about 9.5-12.5 cst at 100c. Mobil 1 30 weights are forumlated on the light end of the 30 weight scale at about 10.5 cst, so are nearly 20 weight. By contrast BMW's relabled Castrol 30 weight is about 12.2 cst, which is nearly a 40 weight. As a rule of thumb, Mobil formulates on the light end of any grade, Amsoil on the heavy end.

6) Redline is a great race oil. For street use it does not work well for extended intervals. The problem is that their chemestry is very old and the oil tends to oxidate quickly and generate higher wear number than Mobil 1 or Amsoil when used in street vehicles.

7) The best widely available oils for your BMW. 1) Mobil 1 0w-40, 2) BMW 5w30 synth. Why the Group III BMW oil that is only LL-98 approved. It is because the 15k interval used by BMW is to far for even Mobil 1 oils under most conditions, so either oil should be changed at 10k or less intervals. As it is easiest to just change once between the indicator lights (about 7.5k miles) the advantage that Group IV oils have over the BMW labled oils are largely negated.

8) You want Mobil 1 0w-40 but cant find it. Mobil 1 5w-40 Truck and SUV will work fine. Note it is not not BMW LL approved or ACEA A3 rated, but meets the spec with an HTHS of 4.1.