kmn2ps1, I have used amsoil,and redline in my primary and this last service I used HD Formula+ and I actually like it better. I am saying this based on the fact that it seems to make less noise when I engage first gear. I never had any problem with my primary, shifting or finding neutral. I also use it in my 95 Heritage which goes into gear like butter and shifts very smoothly. I have 75-140 Amsoil in both transmissions. I cannot notice any difference between redline shockproof and Amsoil in the transmissions. Although I would not use SYN3 in any of my bikes I am really considering going back to HD Dino 20-50 next oil change in both bikes which now have Amsoil straight 60 WT synthetic which works fine, but since my friend , who I have mentioned before, got 180K out of his 2001 Heritage softail using Dino 20-50 before his balancers went out on him.( I know most of you know this, but his engine is rigid mounted to bike that is why they use the balancers) I don't see the need to spend the extra money on Synthetic if you service your bike on a regular basis. JMHO. Any comments would be appreciated. CAHDBIKER