On Fri, 19 Jun 2009 10:43:10 -0500, RB wrote:

dpb wrote:
wrote:
...
For 4 stroke engines do NOT use standard automotive engine oil as it
has no zinc compounds in it any more for extreme
pressure/anti-friction. It has been taken out for emission control
reasons - if the engine burns any oil with the zinc compounds in it,
the catalist is compromized. Apparently it is still allowed in the
heavier oils like 20W50, but that doesnt mean the brand you use will
have it. The special 4 stroke equipment and bike oils still have it.
Use them
for best engine life.

BS...a small 4-cycle engine has higher lubrication demands than an
automotive engine? I don't think so and B&S doesn't either...

"Briggs & Stratton lawnmower oil is formulated...and approved by Briggs
& Stratton engineers-Warranty certified and recommended in all Briggs &
Stratton manuals-A high quality detergent oil classified SJ/CD by the API"

The API classification is nothing different than that for most modern
automotive applications.

I seriously doubt you'll find any ordinary small 4-cycle engine have any
special requirements more stringent than the above.

Air-cooled engines always have hotspots, no matter how well-designed.
That's why even Porsche and VW eventually gave up on air-cooled engines.

Briggs is not going to spec anything other than regular oil.
It would be a marketing nightmare for them, and a warranty issue.
"Don't buy a mower with a B&S engine. You have to use B&S oil, and that
stuff is expensive." They know that the original owner is rarely going
to put enough hours on the engine to wear it out, and even then it won't
be blamed on anything in particular. How many people are going to run a
mower 10 years until it just won't run anymore, then realize "If only I
had used motorcyle oil I'd get another 5 years out of it." ?

As to wear additives, it's true that the best of them has been
eliminated for the sake of emissions, specifically catalytic convertors.
That's a great tip on using bike oils. I'm going to check with my Lucas
rep and see if their Motorcycle Synthetics will work in my non-catalyst
cars. I think racing oils should also still have the anti-wear zinc and
other additives.

They do. So do most deisel engine oils.