On Fri, 19 Jun 2009 18:49:24 -0500, dpb wrote:


Current API specs have all but eliminated the traditional, and most
effective wear reducing additives so as not to foul your cat convertor.
To get the wear inhibitors back, you have to look at oils made for
engines without catalysts - race cars, motorcycles.

That doesn't mean that there aren't different than the traditional wear
additives currently in those oils. There are some very smart folks
doing lubrication design these days w/ far more sophisticated chemical
modeling tools, etc., than in those days of yore.

There are a lot of very intelligent mechanical engineers convincing
the automotive manufacturers to go to the more complex and expensive
roller tappet camshafts to make engines last running the de-contented
engine oils mandated by the emission control requirements.

Will small engines last a long time using motor oils formulated tot he
current API spec?
Undoubtedly.

Are they ideal for the application?
No, they are designed to a different operating environment.

Is the engine manufacturers branded oil the best for their engines?
Not necessarily.

But usually. They will be providing oils with lots of ZDDP in them.
GENERALLY the small engine manufactur supplied oil is roughly
equivalent to multi-fleet or racing oil.

OTOH, is some other selected ad hoc oil any better? Not necessarily.


The primary disagreement I have is the conclusion drawn that OEMs simply
more or less randomly select something in making those recommendations
and that there is something somehow wrong w/ newer oils simply because
they don't necessarily use the older formulations.

Again, specialty applications are something different than the ordinary
small 4-cycle.

Are you a mechanic? In particular a small engine mechanic? Or a
mechanical or lubrication engineer? I'm not an engineer, but I AM a
mechanic (among other things) and have worked on a lot of small and
air-cooled engines in the last 45 years.