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What motor oil should I use?
This question was posed on the club's Discussion
board in the Clubhouse. Read the response from Al Eden, a long-time
Simplicity dealer (see more info). I've posted it here for easy access.
Subject: RE: What oil for B-10
Posted: 1/5/2001 9:10:12 PM
Both Briggs and Kohler call out SAE 30 for Summer and accept multi-grade for
Winter. Kohler also has a CAUTION with their recommendation. They say that excessive
oil consumption and excessive carbon build up may result when you have the
multigrade in. In service schools for both manufacturers both are adamant that
Multi-grade is not "tough" enough to stand up to the aid cooled
The exception is the Kohler Commands and the TH engines they call out 10W-30 for
Summer. First they have hydraulic lifters [350 Chev] and have addressed the
cooling problems that cause oil breakdown in the L head engines. When I first
became a dealer about 20 years ago, I bought a 7117 and used it for a demo. Oil
just ran through it, I called Kohler and they asked me if I read the manual [No]
then they explained to me about oil and heat. I read the manual and changed the
oil to 30 and consumption stopped.
The problem is with the L head design. The cylinder in the area around the
exhaust valve is extremely hot compared to the rest of the cylinder. Multi-grade
breaks down in this area. Multigrade can not handle these temperatures, and
10w-40 is not as tough as 10w-30 to my surprise.
In the new Commands and TH the overhead valve design moves this heat from the
cylinder wall up to the cylinder head. This allows the cylinder to cool more
uniformly. The operating oil temperatures in these engines are much lower than
the L heads. This is why almost all of the L head engines will be gone after
this year. With all of these temp variations they can't meet the ever tightening
emissions standards. This has been one of the biggest benefits of the TH engine.
The fact that there is no head gasket reduces the temperature variations from
the top of the cylinder and the head. Lower and more controlled emissions, this
temp break at the cylinder head has been a problem with emissions. Much has been
done with moving the ring up in the piston, ring thickness, etc. because this
little area along the side of the piston above the rings at the top of the
cylinder that is out of the flame front doesn't burn the fuel properly. Controlling
the temperatures helps and also allows multi-grade oil to survive in air cooled
Sorry -- you ask for the time and I tried to tell you how to build a watch.