This is not so much of a oil brand as a type. I have been running Amsoil in my primary and changing it every other oil change. This time I decided to go with a heavy duty diesel oil and change is every 5 with the motor oil. Cost is roughly the same. I think with the amount of clutch material floating in the oil I would rather change it more often. When I raced dirt bikes (2 stroke) I changed the transmission oil (ATF) after every ride.

 

I will not use synthetic oil in the primary. I have used 15w40 Rotella T for years, I change it twice a season.

 

Thanks, I will be in your neck of the woods this Sept. Thinking of renting a bike and riding the dragon.

 

I' used syn in primary & my clutch slipped. Changed it back to HD Formula+ & it stopped. I do run full syn in engine & trans. I also do all 3 fluids every 5K.

 

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When i was doing motor oil research for a project i was working on in the classic car/motor field chemists & engineers @ mult oil mfgs told me they in fact are now using friction modifiers in many motors oils & diesel oils too .

So point there is fric mod's are just used in lower visc fuel saving oils which used to be the norm in the past which isnt the case today.

But the issue with fric mods is they are not best choice for wet clutch app's because in some cases they can lead to premature clutch slippage.

Why dont you just use proper prim case oil like for ex spectro mfg's thats specifically designed & formulated for lrg disp HD v-twin primary cases?

BTW,it was a good choice you made to go from 10k to 5k mile prim case oil changes because prim oil gets very saturated with metal particles from compensator,prim chain & gears,clutch setup along with plenty of material from clutch plates too often smelling burnt too.

Dont get me wrong,prim case oil still comes out looking dirty @ 5k miles but not near as dirty ,contaminated & burnt smelling as it does at 10k miles.

So ensuring there's always cleaner oil in the prim case can only help all components lubed by the prim oil to have a longer srv'c life.

Happy motoring.

Scott

BTW,pasted below you will see a description & link to the proper prim case oil for your bike that on pg-4 under motorcycle oil tab.

I also run spectro's motor (semi blend or full syn 20w-50) & trans (75-140 for 6spd) oil thats also specifically engineered & formulated for lrg disp HD v-twins. (On same page as prim case oil.)

http://performanceoilstore.com/products.asp?cat=65&pg=4

Spectro Heavy Duty Primary Chaincase Oil 1-qt. This sheer stable petroleum is designed to withstand the punishment of high loads, and contains special polymers to provide exceptional clutch engagement and temperature stability. Meets full OEM requirements, and should be used according to manufacturers’ instructions. Formulated specifically for Harley® Big Twin applications. Low drag, low friction loss SAE 85w viscosity helps eliminate clutch “drag” and slipping.
Price: $7.95

 

Does anyone use penrite oils for engine ,primary and transmission? Would like to know from down under 2008 dyna .

 

I found I had clutch slippage using synthetic in my primary as well. Several years ago I switched to Bel Ray Primary fluid and haven’t looked back. It works great.

 

Hey @Tim Reader , besides this being a 6 year old thread, you may have better luck getting a solid answer to your question in the "Oil and Oil Related" threads located here........

https://www.hdforums.com/forum/oil-a...ted-topics-30/

Hope that helps.

 

oh wow..a good ole oil thread..and in the middle of winter. most appropriate.

 

I have never had my clutch slip running Mobil V-Twin or Harleys primary or even their new gear oil for trans and primarys. But i have always ran a motorcycle only oil in there. Just surpised so many people have had this problem.

I have run Spectro and Redline products with out a problem too.