Rotella T 15w40

“For heavy-duty transmission applications, ROTELLA T Multigrade SAE 15W-40 with Advanced Soot
Control meets the requirements of the Allison C-4 transmission oil specification. The manufacturers’
recommendations should be consulted for specific types and equipment models and for appropriate
temperature range applications.”

I’ve heard of people just using whatever oil they use in there engine in there primary. When I was at Harley saying I was going to change all my oil (2008 Nightster) the guy handed me four quarts of Harley’s goop. I’m assuming he gave me four quarts so I use three in the engine and one in the primary.

Long story short, I recently have switched to Rotella T 15w40 for engine and read the above quote from Shell. Is this ok to use in the transmission?

 

15w-40 in the motor? Glad ur not my mechanic. U must really like the sound of ur valve train. I don't know what 2 suggest u run in the primary/transmission cavity maybe search the shelves of ur garage 4 sumthin with the label missing and dump that in since those stupid dealership personnel havnt a clue. im just kidding u do whatever u want its obvious ur going 2 anyway. So you know I've never needed 2 drop th viscosity below 20-50 even when starting and riding at 14 below zero but what do i know. have fun and ridesafe

 

I wouldn't hesitate to run the Rotella in the Primary since it is a low demand application, but I would stick to a 20w-50 in the motor and a gear oil in the tranny. The brand choices are yours. I think the key is adhering to the recommended change intervals and using the proper weight specified.

 

I inherited a 5 gallon bucket from a job years ago. Put it in two cars and both started leaving spots on my driveway. One of them was a fairly new car.

Over a decade later that bucket still sits in my garage wasting space.

You do know there is a stator in that primary, don't you? And clutch disks that can slip? Besides, the 40w is all wrong for either of your suggested applications.

Rotella is designed for the big diesel trucks.

 

HDEO 15w40 diesel motor oils meet Harley specs for your engine. Lots of guys use it in their primary as well with no adverse effects. But personally, I aways ran HD Syn3 20w50 in my 883 because of the shared trans/primary sump. The 40w oil will shear pretty fast in a gearbox so don't run it longer than 2500 miles.

 

Why would you want to? There are so many choices available.
Why would someone purposely choose to run something designed for other applications? It's on the next shelf in the same store at similar prices?

Why?
When did HD start recommending 15w 40?

 

They don't but they do recomend it if you are unable to find a 20w50 that meets the spec. Check your owners manual. The 15w40 diesel oils meet the same specs the Harley oils do. BTW, Rotella is about $10.50 a gallon at Walmart.

 

quite surprised peppi hasn't chimed in here yet! :-)

 

There is plenty of 20w50 on the shelf next to the Rotella. He he!

Run what you want, I was just asking a simple question.

With all the choices available, why choose truck oil?
I'm not interested in all the "what if" scenarios. Good oil is plentiful and available most anywhere.

Now that you threw cost into the discussion, perhaps that is the answer I was looking for.
Spend 20 thou on a bike, cheap out on the oil, then demand years of wonderful pleasure from the bike. Bad answer.

 

Harley recommends 10/40 wt oil in the motor if its used in temps under 40 f. So using a 15/40 wt won't hurt anything.,,