+1 on that. Shockproof in the tranny proved to be a big improvement. Easier shifting, finding neutral was easier.

 

M1 20/50 in my primary since the first fluid change. Haven't noticed any downside, but I have never used anything else.

 

As was mentioned, there are many opinion's on this subject. I can tell you this. I have been using redline MTL since I bought my 07 streeglide. I noticed a howling noise coming from my primary for over a year! I thought it was the A.I.M clutch device I installed when I went to a 103. Come to find out I had a bad main shaft bearing! I truly believe that if I was'nt running the mtl, the bearing would have exploded causing major damage and possible rear tire lockup! My thought's are that by running mtl it ran cooler, lubricated better, and being a synthetic, held up much better that convetional oil. I won't use anything else.

 

07ROADHAWG
Used 20-50 for a while and had tons of clunk and didn't really like the feel of the clutch.
Switched to Formula+ and was much better.
Since I can't leave anything alone (and after reading about it here), I then switched to Type-F (pick the brand you like) and am really happy with it thus far. I decided on it over the Dex III due to no friction modifiers in the Type-F, and seeing Type-F recommended by a few different clutch disc manufacturers. No slipping and good feel in slow speed maneuvers. With a good clutch adjustment, I don't get any first gear clunk despite what others say. B&M Trick Shift has been mentioned as well, and the bottle says it is suitable for a transmission that specifies Type-F. Valvoline was 1/2 price of B&M so I used the "less is more" philosophy on it.
I think, like many others, that M1 (or any other high tech synthetic) is probably overkill in the primary. The main function of the oil in there is cooling the clutch pack and providing a little lube to the chain and bearing. So a high tech oil isn't necessary, but does make it simpler just to dump in the same oil as the engine and be done with it I guess.

This seems to go round and round but you sound like you have some experience. I have been running Harley Syn3 in engine,75-90 Synethic in transmission and Formula 1 in primary. Would not mind not hearing less a clunk going in 1st but not really sure why you think Type F would reduce it. I know the 75-90 Syn is thinner then Formula 1 and when I put in in transmission it clunks a tad louder and I had read try 75-140Syn. I ride year round and need an oil to suit 99 degrees to 35 degrees and I was thinking the 140 may cause shift problems in the winter. Is you line of thinking that the type F helps the clutch plates disengage due to oil windage and therefore less clunk shifting into first?

 

The post that referenced what Mobil techs recommended seems to make sense. Wet clutches in other applications usually recommend 10W40. 10W40 oils typically do not have friction modifiers (like moly). Avoid any oil labeled "energy conserving" as these oils typically do include moly additives and that isn't a friendly mix for clutch plates. I am sure that most of the oils recommended here to include the HD brand do not contain friction modifiers.

 

It's your money, but any cheap motoroil is just fine as is type F ATF.

 

I just did my service on mine. Schaffers 7000 racing 20-50 in the engine. Redline in the trans and Mobile 1 atf in the primary. Never going back to anything else.

 

Redline has something that they market as v-twin primary oil. The rest of their stuff works great, so I gave it a try. I could tell a difference in the clutch right away, as it seemed to be more progressive with a better feel. I looked on their site and it said this was basically 70w80 synthetic gear oil repackaged as this stuff. Whatever, but it seems to work fine. The manual says you need 38 oz, so you have to buy 2 qts.

 

Look in your owners manual. It recommends Formula+ or Syn3 20W50 Oil.
So I would think the Amsoil 20W50 V-twin would be fine for it. I just switched back to Amsoil from Mobil 1 I'm still using Redline Heavy Shockproof in the tranny. Amsoil 20W50 everywhere else. IMO, I think ATF is too light for the primary, Plus if you overheat ATF it ruins it. These engines do get hot!

 

I just read an article by Joe Minton in the June issue of American Rider about big twin clutches. In it he says that ATF is the best for smooth shifts but worst for your wallet. Clutch wear is not a problem but decreased chain and sprocket life are. He also says gear oil is to thick and causes the plates to stick. So a compromise like Formula + is best in the long run.