...But I just got a note from Castrol extolling the virtues of Castrol Edge. New, better, highest protection, highest quality, beats Mobil 1 on wear protection, blah, blah, blah... .

I just wanna know -- it meets ACEA A5,B5, and they say it's good for 15,000 miles. Is this stuff any better for my '06 325Ci than Castrol Syntec Euro, or Mobil 1 0W-40? Both of those meet LL-01 and ACEA A3,B3. I've seen something saying that A5,B5 isn't as strict on the HTHS requirements as A3,B3. It's just a little confusing to me because all of the older, lower SAE ratings are incorporated into the newer ratings, at least so far as I know. That is, oil meeting the newer SF rating, for example, would always meet all the lower SC, SD, and SE ratings. So how is it that ACEA A5,B5 oil does NOT meet A3,B3? Or am I missing something. I've got an oil change coming up in a few hundred miles, and like most of you, I want to use the best stuff for my engine. Right now, it's a toss up between Mobil 1 0W-40 or Castrol Euro. (And no, sorry guys -- I don't want to re-start the discussion about Royal Purple, Amsoil, or any of those.) But if this Castrol Edge is so much better, and if it's right for my car, I'll want to use that. Any of you oil experts got any help for me here? Thanks in advance for your time.

ACEA A5 and ACEA A3 are two different specs, and it is not possible for the same oil to meet both for the simple reason that ACEA A5 requires the HT/HS to be below 3.5, while ACEA A3 requires the HT/HS to be 3.5 and higher.

That is also why an ACEA A5 oil cannot meet the BMW LL01 spec, because again, the LL01 spec requires the HT/HS to be 3.5 or higher.

And so, for this reason, if you want to stay compliant with your mfg warranty, you should be using LL01 oil in your car. This means GC 0w-30 or M1 0w-40. Castrol Edge does not meet this requirement.

Just use the Mobil 1 0w40 and stop worrying.

Castrol's claim regarding better protection, even if true, pertain to an entirely different viscosity than the oils you're discussing, and thus is irrelevant.

Truth be told, you could use any of the oils and I would guess that you would see absolutely no difference over the course of your ownership of the car.

Others may have different opinions.

Cheers,

Jeff

As Quattro Pete mentioned, the ACEA sequences are not in place as a progressive improvement. A1 isn't superseded by A2 which isn't superseded by A3, etc.

The specifications are simply in place to meet differing demands. If you need a A3 oil then use a A3 oil. If A5 is the requirement then that is what you should use. The specs have actually been replaced with C1, C2, and C3 for the past few years just to throw us a curve.

As for the Castrol Edge that is sold in the USA? This oil is a very low viscosity product and seems to be aimed at meeting fuel economy standards rather than European builder approvals. With a viscosity of 9.8 Cst's @ 100ºC, the oil is light. It probably has a HT/HS viscosity of 2.9 or thereabouts and should fit nicely into the ACEA A5 category. However, BMW doesn't specify this requirement and chooses a higher viscosity product for their engines.

If you just use your car to drive to work and back then I am certain that you'll not suffer any issues by using a product like the Castrol Edge. Even placing a phone call to BMWNA will give you their verbal go-ahead to use any synthetic oil such as Mobil-1.

After driving a E46 for the past 10 years it doesn't seem to make a whole lot of difference what oil you put in. My engine has been happy with products ranging from 0W-30 Mobil-1 to 5W-40 Redline and all synthetic grades in between. It does show a difference on the fuel economy display when using heavy oils but amazingly I have seen the best economy using Castrol Syntec 5W-40. Go figure. Some oils have carried BMW approval and some haven't. The engine is ticking along just fine with ten model years passing and it's still purring like a Bavarian kätzchen (kitty).

Thanks all for the info and opinions....much appreciated...