Hi all,
I was looking at the manual for my wife's 1994 BMW 525i and noting the recommended oil weights. It is interesting to note that 20w-50 is approved for temps of up to 120F, 15w-50 to temps of 100F, and 10w-50 to 80F. As I had posted before, BMW now says that I can run BMW brand, Mobil 1, or Castrol Synthetic in 5w-30 weight year round (in the manual 5w-30 is only approved up to 40F).
Given that all Xw-50 weights should be the same thickness at operating temperature, I have to wonder if the reason that the German manufactures recommended such thick oil was due to concerns of high operating temperatures, and the oil burning off and sludging. The temp restriction on wide spread oils with lots of viscosity modifies (i.e. most likely to sludge) seems to indicate this. I have to wonder if the engines are really fine with 5w-30 synthetic and by going to synthetic, the sludging concerns are eliminated. I tend to think this because I remember in the 1980's when it seemed that every Mercedes imported from Germany had serious sludge issues.
What does the group think of this long rambling idea?
Cary
I was looking at the manual for my wife's 1994 BMW 525i and noting the recommended oil weights. It is interesting to note that 20w-50 is approved for temps of up to 120F, 15w-50 to temps of 100F, and 10w-50 to 80F. As I had posted before, BMW now says that I can run BMW brand, Mobil 1, or Castrol Synthetic in 5w-30 weight year round (in the manual 5w-30 is only approved up to 40F).
Given that all Xw-50 weights should be the same thickness at operating temperature, I have to wonder if the reason that the German manufactures recommended such thick oil was due to concerns of high operating temperatures, and the oil burning off and sludging. The temp restriction on wide spread oils with lots of viscosity modifies (i.e. most likely to sludge) seems to indicate this. I have to wonder if the engines are really fine with 5w-30 synthetic and by going to synthetic, the sludging concerns are eliminated. I tend to think this because I remember in the 1980's when it seemed that every Mercedes imported from Germany had serious sludge issues.
What does the group think of this long rambling idea?
Cary