I actually don't want to bring this up... but it's too late.
Yeah... But is it 20w50 car oil (SJ rating)... or 20w50 BIKE oil.??
This topic has been beat to death a lot.
But the truth is that car oil has changed in the last 5 years... For 2 reasons... Both government related.
The US gov specified "oxygenated" fuel for some parts of the country..
Oxygenated fuels get worse gas mileage.
So car manufacturers specified slipperier oils to get back some of that lost mileage.
Slipperier oils CAN cause motorcycle wet clutches to slip.
The US gov also has demanded that car manufacturers make their pollution control catalytic converters last to 100,000 miles.
And the main thing that killed catcons were "high pressure" anti-wear additives in oil... (which protect your engine under high temp hard useage times)
So they removed them from car oils.
And bikes typically run 50 to 100 degree F higher oil temperatures.
So....I have run "car oils" for years.... But.... They are not the same as they used to be.
The oil manufacturers have recommended using "bike specific oils" that don't have these changes.
Even new bike owners manuals do not specify the "SJ" oils (car oils with the press add's removed and slipperier base).
So... Those of us that have run car oils now have to make a decision of whether to believe the "Oil manu's"... and pay two or three times as much... Or?
So far I am using the "SJ" rated car oils.... My clutch now makes a funny "graauuunch" sound under hard engagement conditions (drag type starts)
But I'm not sure that's because of the oil or not.
And I CAN"T find the old oils my engines manuals call for ..."SE", "SF", and "SG".
Unless I go to a bike oil.
That is the state of the state of the oil situation.