I'm putting an auto primary chain adjuster on the bike. Normally I run Syn 3 in the primary but today I bought the HD blend.

My question is why do you need synthetic in the primary? Is there an advantage?

Thanks guys. After 30 years of playing with bikes with primary cases & all I have usually used is good old ATF.

I think if an Auto' box with multiple clutch packs, Sun gears etc, can run for over 100,000 kms without changing oil,
the ATF in a HD primary would have a very easy life.
You can buy synthetic ATF now as well.

Is it worth it? Why not just use what the HD engineers have tested and certified? If ATF did the job long term I am sure HD woulda come out with it too as it would earn a good quid.

I tried one of those you beaut oil additives once that had every test under the sunin cars 'n' bikes to validate it and even tests run after dropping oil (so they said) to show how it protected the parts. Well faaaark me if it didnt absiolutely fuck me clutch within 500km's!

i gotta buy oil anyway and there aint no great saving going to Kmart for my baby!

 

been using atf in my primary for years and never had a problem,

I tried ATF in my primary a few years ago and found it was a lot thinner than oil, and it started to seep around the gaskets a bit because of being so thin. Took it out and put the recommended oil back in and the seeping stopped. Granted, I probably should have replaced the gaskets but at the time draining it and refilling with 20W50 was a quicker and cheaper option, and it worked. Havent had even the hint of a gasket seep since.