PeachParts Mercedes-Benz Forum - View Single Post - 15W40 Vs. 10W40 Pro's/Con's, Which ones BETTER?

waybomb · #7 09-11-2006, 10:03 PM

FWIW: ALL available standard gas engine lubrication oils are not the same as they were 5 years ago. ZDDP has been removed to a level of almost non-existence. ZDDP (essentially Zinc) has been removed because the EPA has decided the ZDDP was a cause of failed CATs.

The only way to get gas engine lubrication oil with a full complement of ZDDP is to by "Off Road Only Racing Oil". Regular old "Racing Oil" also has had ZDDP removed to the same level as regular oil.

This loss of ZDDP is not a problem to modern engines with roller camshafts. It is a BIG problem to those of us with flat tappet cams with higher spring pressures, such as in high horsepower engines. Many of us gearheads with flat tappet camshafts found out the hard way in the last few years by having our cam lobes go round, and lifters becoming short, with all that lost metal getting circulated in the engines. Some of us have been fortunate enough to build the engines using high performance oil filters, catching the errant metal particles before wiping out expensive steel cranks.

All flat tappet cam shaft manufacturers now recommend use of Delo, Delvac or Rotella in flat tappet gas engines, or, "Off Road Only Racing Oil", and specifically warn against using regular engine oil and oils labeled "Racing Oil".

After wiping out all three camshafts in Plain Vanilla (this gets expensive!) (It was weird - all three had round lobes within a few engine hours of each other, so I knew something unusual was in play) because I used premium grade gas engine "Racing Oil", and not knowing about the removal of ZDDP, and the effects of that removal, I now use 15w-40 Diesel Oil, Rotella T, in all my engines. Knock on wood, no problems yet. If I plug a CAT, well, I guess I'll install a test pipe to see if the CAT was plugged and simply forget about having installed the test pipe.