The only unique requirements you absolutely need to hit are to avoid the clutch slippage causing energy star additives, get over 10 PPM of ZDDP to keep from tearing up your flat tappet cam lobe junctions (antique valve actuation technology that is still used in the 1980's designed Savage motor) and get you a synthetic oil so if your air cooled motor gets overheated accidentally your oil and your Savage doesn't self destruct.
This mix of stuff is generally found in expensive motorcycle oils (over $10 a quart) or in diesel oils (much less expensive as big diesel engines use 5-10 gallons of oil to make an oil change).
Diesels have very heavy duty requirements as they can go 80,000 to 100,000 miles between oil changes and live with much heavier bearing loads and temperatures than are seen anywhere in a car (or most bikes for that matter).
That's why bike guys like diesel oils, they can
exceed the requirements of our bike engines at a relatively lower cost.
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BTW, I am a fan of the first oil on the list of BEST OILS that you discovered independently on your very own. The cost per oil change for that oil is the lowest of any and the protection provided is arguably as good as anything out there.
You can pay a lot more, but do you get anything for paying the extra money?
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There is a reason that this stuff has become #1 best oil in motorcycledom and has survived every oil war on every list (and at BOBISTHEOILGUY and their endless professional level oil wars) at the top of everybody's list of best oils.
And yes, it has been subjected to JSO tests repeatedly and passed, so the Jap motorcycle mgfs do "approve" of the use of certain diesel oils in motorcycle engines.
Some honest Honda/Kawasaki/Suzuki/Yamaha dealers even recognize that car oils have moved away from being good motorcycle oils due to the issues with car catalytic converter contamination and will actually recommend and sell diesel oils on their showroom floors. Mine does, right next to the $14.95 a quart motorcycle oils.
And guess which one he sells?
The one that protects best against
EXTREME temperatures, of course.