I was curious if anyone had any opinions/experiences about oil weight for

a '92 240.

Manual says 10-30 preferred in all but the hottest climes, then 15-40.

I ordinarily respect mfr's specs, but I'm suspicious of the 10-30 recommendation because I know that mfr's tend to recommend lighter weight oils in order to squeeze the last few 1/10ths on MPG ratings. Also, none of the brands I prefer seem to be available in 15-40.

I have gotten 350K trouble free miles using 10-40 in my '87 240, (10-40 is recommended for this year) and I am planning to do the same with the '92 unless there is a reason not to--specifically, a changes in the engine that would make 10-30 advisable.

Any comments appreciated.

Dave S.