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The best of the breed is made by Red Line. Full synthetic and a great oil.
Checking on Redline's website, the following is posted:
20W60 - Specifically blended for air-cooled V-Twin engines with traditionally wide clearances like Knuckleheads, Shovelheads, and Panheads engines.
20W50 - Designed for the latest Big-Twin motorcycle engines that specify 20W50 motor oil, including including Evolution, Twin Cam, and aftermarket engines of similar design
harley even sells a 60 weight for extreme temperatures. redline 20w60 should work fine-and may quiet down the motor a little. i will be giving it a try down here next summer i nsouth texas.
Used Redline for my Sturgis ride and was very happy with the results of the 20/60. Put 3800 miles out and back and held pressure at idle and highway speeds, when hot.
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