0w30 and 0w40 do not seem to be real suitable for M50s with "advanced" miles. Mine started getting a random idle tick when warm with 0w30 castrol syntec with about 4,500 miles on the fill. I changed to a blend of 10w40 (2 quarts) and 5w50 (4 quarts) castrol syntec and no more warm idle noise.
0w40 mobil 1 was just noisy. I just did not like it. Going to stay with heavier oils, especially in the summer.
Last edited by Russell; 06-14-2007 at 08:11 PM.
Thanks,
1995 525i Auto, M50TU 2.5L, EAT chip, 1/95 build, USA, 205/65/15 tires, ASC+T, HID, lumbar, EC Mirror, BMW Alpine 5 radio with BMW-Pioneer CD Changer, abt 236k miles, Oxford Green/Parchment