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         Should ATF or Motor Oil be Used in a Harley-Davidson Primary
 
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Question:
Should ATF or Motor Oil be Used in a Harley-Davidson Primary
I understand that there are some people who are touting the benefits of using ATF in a Harley primary. What are your thoughts on using ATF in the primary vs your 4T 10W-40 motorcycle oil?
-- Robert Dunn, West Chester, PA

Answer:
Automatic transmission fluid (ATF) would probably work fine in your primary but in the end you will have to decide if you are satisfied with its performance.  Every biker “feels” his shifts and knows his sensitivity to clutch slippage. Every modern ATF is designed with specific frictional characteristics that complement transmission performance with very specific friction materials. Depending on which fluid you choose, you may or may not be satisfied. And even then your buddy may try the same fluid and have yet a different opinion.