I read somewhere on here that some guys are using Rotella 15/40 diesel engine oil in the primary and or trans. I will tell you this, when I worked at Jasper Engines we specified Rotella for the Borg Warner T5 transmissions. Completely eliminated the overheating of 5th gear. Factory was automatic transmission fluid. Any thoughts?


p.s. some guy left a gallon of the Rotella in a vehicle I traded and was wondering what to do with it.

 

I am thinking if I had a relative new Rushmore bike why I would do that. Harley engineers recommend diesel grade oil products when it's the only thing you can fine. They also say to replace it as soon as you get the chance. Sure, they are plenty of grandpa stores of it works. I even use it in my Yamaha but could care less how long it last.

 

I've heard very good things about Rotella in the Primary. It has the JASO spec too!

 

That's what I used in my evo softail and now in my 2015 Ultra. I think it makes neutral easier to find and the clutch doesn't seem to drag when cold starting.

 

Stick with Formula Plus in the primary. It's only about $9.00 a quart and works very well with the factory's clutch plates.

Mortor oil--your choice there. Transmission--Redline Shockproof

 

I use Rotella in my dirt bikes engine and transmission I've never had an issue with any of them ever. But I really like the formula plus in the chain case on my SGS it runs so quiet with it. My bike had some issues the day I went to leave for Sturgis this year and my buddy loaned me his Electra glide to go on my trip. When I got home I did a full oil change on it and I put formula plus in the trans and chain case and was amazed at how much quieter it was afterwards.

 

Wasn't really the question and kinda a dig to the OP when he's asking a simple question.
By your reasoning none of us should ever change anything on these bikes including exhaust. Harley engineers designed those.

To answer the OP, it will work fine. Many use it. I use Formula+.

 

Most of these oil threads start off from tin men. Since it says right in the service manual to only use it when the proper oil is not available, my comment was meant for a tin man. However, you are right.

Sorry Magnut...

 

Been using it on both bikes for 3 years. Works for me.

 

No p Ripsaw. Thanks to all who posted. I have this $60 jug of Rotella and thought I would use it up instead of having it sit on my shelf. My choice is synthetic oil, SYN3 or Mobile 1 in the engine, and the Rotella in the trans and primary. They are due and I will change them both at the same time and see how it goes. Not sure when I will get er done but in the next week or so, and will let you know. Worse that can happen it doesn't work, then I will know, and I can always change it out.