what viscocity are you guys using? i used 10w30, and my oil broke down in 1500 miles, so obviously i need to go thicker. any help is appreciated

Just curious, how did you determine that your oil has "broken down"?

from CA and I use RP 15W40

Just curious, how did you determine that your oil has "broken down"?

I'm likewise curious.

Your owner's manual (or the Bentley service manual) will have a chart of recommended oil viscosity for temperature ranges. Out here in CA, I'm using 15w40.

seeing that your in Chicago you need to se lighter in the winter and that you have a 3 you have a small six or a 4 banger so you need lighter there.....im new to bmw's so i cant be as acurate but id use 0W40 in winter and a 5w40 in summer and if you like to push your car 5w40 in winter and 10w40 in summer

also if your not getting the life out of your oil go with a synthetic or mobil 5000 lasts like 5000+ miles in my brothers 528i(i use syn, lasts 15k)

Mobil 1 10W-30. I have only changed it once and getting ready for my 2nd oil change on the car. I am though, sending my oil off to Blackstone labs as I am curious what the oil is like and what the inside of my engine is like after 10K between oil changes.

See my post in the E36 M3 board, http://forums.bimmerforums.com/forum/showthread.php?t=535032

The 10w-30 you're using doesn't provide enough viscosity.

This would apply to the M50/M52 engine family as well.