I'm posting the front and back labels for Valvoline SynPower Full Synthetc 75W-140 gear oil, because this oil can be used in Harley Davidson transmissions. Your bike will shift better and sound better if you use a heavier gear oil in the transmission. I think most people use Harley Davidson 20W-50 SYN3 motor oil for the tranny, which Harley Davidson started recommending a few years ago because its convenient, but its a trade off for the Harley owner. I believe your trading a better manual transmission gear oil for the convenience of only needing one type of oil for the motor, transmission and primary, which isn't a good deal in my opinion. Even Harley Davidson now offers a full synthetic 80W-140 gear oil for use in manual transmissions.
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