Quote:
|
Originally Posted by weasel56
I use the BMW oil as it is convenient for me working there and all, and don't remember the price off hand, but it should be about the same per quart as any top brand full synthetic.
As for the ow-40 vs 5w-30, the second # is the viscosity at full cold (ambient temperature) and the 1st # is the operating temperature viscosity. Being where you have extreme colds (at least vs the mild south I'm in where the shop had the AC on today)... The 40 weight would be thicker than oem at cold, but thinner when hot. It seems to me the 5w-30 would be better. Maybe someone with more cold weather/oil knowledge will chime in though.
|
I use the BMW 5w-30 oil as well, and find that it is a similar price to other oils. It is convenient since I pick up a filter at the same time.
The viscosity numbers are backwards, above. A 5w-30 acts like a 5 weight oil during cold starts (tested at 0 C), and like a 30 weight oil at operating temperatures (tested at 100 C). Thus, the 0w-40 is thinner than the 5w-30 when cold, not thicker. However, the 5w-30 oil is fine at the temperatures the OP is likely to reach (depending on where he is located). The pour point is probably around -50 or so. At -40 and with cold starts I would be looking for a 0w oil, as it isn't just a matter of the pour point, the oil will be thicker at lower temperatures. You have to start looking at other test criteria then.
__________________
2007 X3 3.0si, 6 MT, Premium, White
Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue
Last edited by JCL; 02-11-2009 at 01:56 AM.
|