If you are using motor oil you can put 20-50 in all 3 holes. Some folks run gear oil in the tranny, but don't put that in the primary that has to have motor oil or HD formula stuff for the primary.

Do a search or just read through some of this thread and you'll see what folks are using.

 

I ordered Redline last night, Trans oil w/Shockproof and primary oil which has a viscosity rating of 70w80, says it's for 1984-present Evolution, Twin Cam, and aftermarket engines of similar design.

 

I just made the switch from Formula+ over to Redline Shockproof Heavy. I never expected this stuff to be that thick, can you say molasses? As for now I don’t know if I’ll stick with it or not. I’m sure it is good stuff, especially in the Vegas summer heat. I’m thinking that it could be a little too thick in the cooler months. If I don’t stick with it I’ll probably go with something a little lighter for both cool and hot seasons; perhaps the 75W-110 Amsoil or back to the original Formula+. One day at a time…

BTW, it does seem to be a “little bit” better on shift noise and smoother shifting. However, I haven’t noticed a huge difference to consider it “clunk-free” I think some folks exaggerate the clunk think a little too much. The finding neutral thing, hummm

 

I'm not sure but I don't think the Formula + is a synthetic, so if it was me and I was going back to Formula + I would go to a sync 20-50 motorcycle oil. I'm a fan of sync but each to their own.

I myself in the climate I live in find that 10-40 sync motorcycle works really well in the primary, use 20-50 everywhere else. If I'm going on a trip to the southern US I'd probably put 20-50 in the primary as well.

I tend to agree with you as to the clunk & neutral. The clunk & finding neutral is all about where the slack is in the driveline when you are putting it in gear and for finding neutral. Unless the oil is really thick on a cold morning, I don't see how it plays much of any part.

 

I had a nice little chat with a tech at Redline. He said that HD had switched to engine oil for primary for a while and now the manufactures are all switching back to thicker viscosity oils, Redline's primary fluid is 70w80. Hence it explains why the MOCO's trans fluid is ALSO their primary fluid. Just sayin...

 

From a viscosity point of view 80/90 gear oil is the same as 20-50 motor oil. Just that you don't want to use a gear oil in the primary. You can get away with it in the tranny but not the primary.

Every wet clutch Japanese motorcycle ( of which there are millions + ) that share a common sump uses motor oil, those that are water cooled would use a 10-40 weight unless you lived in the desert areas, and then they seem to put in 20-50.

I always try to stay with what the manufacturer recommends as they are the folks that built it. Thats with respect to gear oil or motor oil, weight etc.

 

cycleman11, I disagree that a 80W90 gear lub is the same as a 20W50 engine oil. When I read Amsoil's site their 20W50 motorcycle oil it is pretty much the same viscosity as their 75W110 gear lub at 100 deg.,C. Their gear lub also has a lower pour point then the 20W50 MCV also better in the cold eh. Amsoil's 20W50 motorcycle oil only has a GL1 rating were as the gear lub has a GL5 rating to protect the gears in the trans.. Amsoil's first choice is however for the trans., their 20W50 MCV oil for the trans., and their 2nd choice is the 75W110 as one will see on their site eh. I run their 20W50 MCV in the prim., but may try their 10w40 motorcycle oil in the prim., as years ago that was what they called for in my 1992 FXR prim., but somewhere down the road I guess they changed it to the 20w50 for what ever reason. The prim., sure gets really hot when run long and or hard for sure. Each their own and I am sure some work better in diff., cases eh. Ride safe all and have a great day now eh.

 

I have no problem with somebody disagreeing with me. I just refer folks to the Bob the Oil Guy site as they have a lot of useful info on oils etc and this is were I got the viscosity chart from. Using the following viscosity chart, they both check out at the same viscosity:


No matter what, you don't want to use a gear oil in the primary. As you've noted Amsoil doesn't recommend gear lube in the HD primary/tranny nor does Mobil 1. There are only helical or straight cut gears in the HD transmission, neither require a GL5 gear oil. You can use a GL5 gear oil in the tranny as their are no yellow metals, but there really is no need from a manufactures/engineering requirement standpoint. The only bike manufacture that I'm aware that requires gear oil in their transmissions is BMW, they recommend a GL5 80-90 weight.

Have a good summer on the bike and ride safe.

 

Question: Even though I just changed all 3 fluids, (have been using Syn 3 in all 3 holes since new), I want to go with the Mobil 1 for the tranny. Since we get some hot weather here, I was thinking of running a 50/50 blend of 75/90 & 75/140. Does anyone see an issue with that?

 

In my '07 Heritage: Mob1 20w-50 in crank; RedLine Heavy in trans; and Mob1 MV Dex+4 atf in the primary with the RiveraPro clutch pac. that combo seemed to work best for that bike.

In the '10 Ultra: Mob1 20w-50 in crank; RedLine Light in trans; and Formula+ in primary (tried 4 different types and for this bike this was the quietest, smoothest, always slip into nuetral anytime).