Hi everyone;
I just baught a '11 Road King and noticed some oil companies sells differents oil for trannies and primaries...But, others makes no distinctions and sell one bottle for both; any idea?

 

Just use gear oil in the trans and not in the primary and you'll be fine.

 

Transmissions tend to shear oil a lot quicker then does an engine or primary.

So for that reason, oil designed for the transmission (and other gear-heavy applications) tend to hold up better then other oils but they tend to cost a bit more too.

While you'll certainly find lots of bikes that use a common oil (engine, tranny, clutch), the differences in requirements doesn't lend one common oil to work really well.

Thank Harley for separating the oils.

 

Tnx for the info! Knowing this, I'll use 3 different oil. But what type of oil goes in the primaries, if it's not gear oil?

 

Primary is not real fussy any reasonable priced 10w40 will work just fine. Some use ATF. Not the best to use a synthetic, I found some clutch slip in the past.

 

I agree with Fort Rider. You don't want to use a motor oil that has a lot of moly it it because that may cause your clutch to slip. I currently have a 15w40 HDEO (Delo 400 diesel oil) in mine.

 

Start with a decent 10w40 oil that's wet-clutch compatible.

For some reason, my '08 UC's primary really likes the Valvoline Motorcycle 4 Stroke 10w40. Clutch operation is smooth and solid.

Your machine may prefer something completely different.

Good luck!