Have 2010 Iron. Have been using Mobil 1 Moto oil 20w50 in primary last 2 years. It seems a little too heavy-especially in the cool mornings. Clutch is properly adjusted, I can find neutral but with clutch pulled in and rocking bike back and forth-there appears to a bit of sticking/dragging. Tried a change to HD primary shifting was worse and clutch action not as smooth. Back to Mobil Moto oil.
Have read that Mobil 1 Moto 10w40 is too light for primary. Would a mix of half and half 10w40 and 20w50 be a workable solution? That is cause no undue harm to the primary workings (gears, bearings etc)? Thanks to anyone who can answer.

 

Motor oil is not ideal for your primary. You should use a good gear oil.

If your a fan of Mobile 1 stuff, you can use this http://www.mobiloil.com/USA-English/..._75W-90LS.aspx

However, it is a GL-5 rated oil which some believe cam be harmful to your stator.

Personally I use http://www.redlineoil.com/product.aspx?pid=46&pcid=7

It's a full synthetic 75w90 made with the highest quality synthetic base. It's also GL-4 rated so it's safe for yellow metals including your stator. the only problem is that its hard to find for some people. I recommend ordering 3 bottles, that will get you through 35k miles.

Perfect clutch engagement and shifting and less clunk. you wont be disappointed

 

The 20W-50 is the correct viscosity (of engine oil) for the primary/transmission. Harley's Formula+ is approximately an 80-weight gear oil (which is equivalent, they're not the same scale). For best results and cost, use what I use:

Attachment 291647

 

Cycle gear stocks that (the MT-90). No shipping charges if one is near by. The one by me will special order stuff too if they do not stock it so ask if it is not on the shelf. The O'Rielly auto parts store I go to will order me anything motorcycle related I ask for too.

Hit up some auto stores, the better ones will special order just about anything. Saves shipping fees.

 

+1 - on the Mobil-1 75w-90 Gear Oil, and for the 10,000th time, it's yellow metal safe.

 

Red Line makes a chain case oil

GL 4 / SAE 70W80

 

Redline actually recommends their MT-90 for the Sporty.

 

Thanks to all for your information. Will be Mobil gear oil first then RL MT90 if not satisfied. Thanks again.