getting ready to change the oil on my 07 nightster for the first time and also going to change the oil in my wifes 04 sporty. my question is do you have to change the primary out or is it all in one when you change the oil? going to change the transmission fluid out as well. I have figured everything out for the out and i think the tranny too just wondering about the primary and if you have to do that too? All help is appreciated

 

Motor oil is motor oil. The Sportster primary and tranny share the same oil. You really need to buy a manual for both your bikes.

 

Yep. On the sportsters the primary and transmission share oil. Only 2 holes on the Sportsters

 

yes i know just havent gotten around to getting them.

 

If you go on utube, someone made a video on changing the oil on the Sportster, pretty good info...and yes the motor oil and the transmission oil is changed by different drains, some on here say to use the same oil in both holes, some recommend different oils, use the search feature and read all about it, good luck...

 

Most In the Know use a thicker Oil in the primary for quieter shifing,,
Synthetics flow like lighter weight Oil's.
Not shure whats best for the primary,,20-50w In the motor,,75 to 90 wt synthetics
In the primary I think,,check this first,,,,

 

Not trying to shoot you down Osco but if I use a reccomended synthetic to replace the OEM oil for better wear characteristics I'll take more noise anyday although usually synthetics make things run quieter!

 

I know it has to have been cover to death, but a fast search didn't come up with it. What are most of you using in the primary/trans ??? I didn't know, so I used a quart of Harley Sportrans.

Be Safe JIM

 

The current "Moco recommended" oil for the primary/tranny is their Formula+, which is a non synthetic Gear Oil.

Gear oils are not "thicker" than motor oils, they are measured on a different scale than motor oils are. A 20-50 Motor oil has about the same viscosity as a 75-90 Gear Oil. (see chart below)

The big difference between Motor oil and Gear oil is the additive package that is in each product. Motor oil is designed to deal with the by-products of the combustion process, while Gear oil is formulated to deal with "shearing" that occurs in gearboxes.

I use Mobil-1 75-90 Gear oil (synthetic) in the primary/tranny.




.