I'm still trying to figure out what synthetic oil (other than Harley brands) to use in my transmission,Twin cam 88. Everything I read on forums says that it is ok to use a synthetic GL1,GL4 or GL5 rated oil ?? Thats fine, but I can't work out where this info comes from ?? I tried to find something in the workshop manual but it only gives two part numbers 99891-84 and 99892-84 and niether of these tell you anything except that one is semi syn oil (syn3) and one is mineral (HD 360) there is no info about the viscosity of oil (or anything else) you can use . So where is the evidence to support using GL1,4 or 5 oil ?? I also rang Amsoil in Victoria and the guy I spoke to said, just because an oil is rated GL5 (for instance) and the transmission you are going to use it for is GL5 rated, does not necessarily mean you can use any or all brands of oil even if they have a GL5 rating ?? Go figure ??

I probably am over thinking it Scotty,and yes I have Redline in it now but I am not very happy with it, just seems to clunk more. I just keep getting varying information from so called experts and it gets frustrating. I don't want to keep changing oil brands all the time so I want to make sure of what I put in it this time. I was going to put Castrol GL5 in it until a guy at Amsoil told me that you should'nt just put any brand of GL5 oil in it. Anyway I think I'll just stick with your advice.

Hi Peter if your clunk is still still there try this in the morning warm your motor up pull the clutch in and out from 3 to 4 time then hold it in count to 10 and slide it into gear  gently not bang it in works well.I run ATF in the primary and full 70-90 syn in the gerabox all the best.Charlie

Thanks, I will try adjusting everything up first but I'm pretty sure all is ok, it hasn't been that long since I've checked. i think it may be a case of winter comming on and the Redline being too thick ?? Not sure but we'll see.

Well, I adjusted the primary chain and the clutch pushrod, and that is not the problem so I will chuck a different oil in there in a few days and see what the change is ?

Hi again Peter try the redine high temp ATF in the primary  its not cheap but my Ultra changes like a automatic well most of the time Ha. I tried the shockproof in the gearbox and my shaft seal leaked changed it to 70-90 mobil syn and new seal now it changes very smooth.I put the article on the gear change i told you about on the last threat in our club newsletter and received some good feedback.Charlie

Thanks Charlie, I'm not worried by the clunk going from neutral into 1st gear, most bikes do that anyway but the bike is generaly a bit more clunky and I get an occasional "very slight" crunch changing from 1st to 2nd gear. So I'll try some new oil and see what happens ??

Almost bought the Nulon, but I ended up putting Castrol Syntrax GL5 in it because its died red and if I get a leak I'll know where its coming from. It is changing smoother than with the redline in it, go figure ?? Just out of interest I also read that GL5 rated oil is harmful to rubber so I wonder what happens if you get a leak from the shaft seal (or wherever) and it leaks onto the belt ??

Now thats just being logical.