I see some people like to run various oil weights in each opening. If a thicker weight is better in the primary and tranny, then why would harley just do the 20-50 in all three? I was thinking of using either mobil 1 or lucas 20-50 in all three openings, is there a problem with that or is it just your personal feeling. I do have an oil cooler FWIW. Thanks,
First, you need to understand the different rating systems. Motor oil is rated on a different scale than gear oil, so the "weight" numbers you refer to are not interchangeable. A 50 "weight" motor oil is about the same actual viscosity as a 90 "weight" gear oil, for instance. The correct rating for your Harley is a 20w50 motor oil, and a 75w90 gear oil.
The difference is basically in the additive packages. Motor oils cannot use some of the best anti-wear additives available in true gear oils due to potential damage to catalytic converters and formation of acids due to moisture from combustion entering the crankcase, among other reasons.
However, if you want to use one product in all three holes, I wouldn't stay awake at night worrying about it. Just make sure you use a product that is formulated for all three holes, which means it does have some additional additives for gears. SYN3, Amsoil, and Mobil 1 all claim to meet the minimum requirements for gearboxes. You'd have to ask the manufacturer about any other brands you might be considering.
Jerry
And btw, yes, this subject has been beaten to death. Try a search on the site, you should get enough hits to keep you busy for a day or two at least. Lubrication is one of those topics that attracts more hype and BS than just about any other topic I can think of, both from those who sell the products as well as those who use them. Don't believe everything you hear or read.
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Topic: why different oils in each opening? (Read 5704 times)