Author Topic: 15-50 motor oil (Read 2932 times)

stillmatick · « **on:** June 28, 2011, 06:47:59 AM »

is this the correct weight oil to use in my m42??

DesktopDave · « **Reply #1 on:** June 28, 2011, 07:10:40 AM »

Not another oil thread!?!?

Just kidding. You'll get 100 answers every time you ask about oil. I believe BMW advises conventional 15w50 in avg summer temps and 10w40 in the winter. It's a sliding temperature scale listed in your owner's manual.

But I'll tell you what I use...whatever 5w30 synthetic is on sale (usually Mobil1 in the five liter at Wallyworld). The thin 30-weight seems to help a bit with fuel mileage and the synthetic keeps the motor pretty clean. I've used 0w20 in cold temps as well...that worked OK but it's pretty thin stuff so I went a bit thicker. Older BMWs tended to run pretty heavy oils; our M42s were built as BMW started the switch to thinner oils. It cuts down on parasitic drag and slightly improves fuel economy.

50 weight oil is pretty heavy for our motors IMHO, but it gets a lot hotter down there than it does up here.

stillmatick · « **Reply #2 on:** June 28, 2011, 07:35:08 AM »

5w30 synthetic and 10w40 mobil1 oil here is always on sale for 30 and down. Guess i hit up autopart store for 15w50 synthetic mobil1,is gonna cost me 60bucks

.

monty23psk · « **Reply #3 on:** June 28, 2011, 08:17:12 AM »

Mobil 1 recommends 0w40. Also BMW long life oil is also 0w40. I just went with is and like it so far. I live in Sunny South Florida so could temps is not an issue for me.

stillmatick · « **Reply #4 on:** June 28, 2011, 04:14:23 PM »

stillmatick · « **Reply #5 on:** June 28, 2011, 04:19:37 PM »

damn,guess i have to return the 15w50 for 0w40.

here more info about oil for bmw
http://edu.cqdx.gov.cn/bmw/134262.html