Conflicting Rear diff fluid info 2011 1500

[bcja]

Hi all,

I have a 2011 1500 Outdoorsman 4x4 with 5.7L Hemi and 5-speed trans. The rear differential has a 3.92 gear ratio and is the anti-spin type.

Getting ready to replace the fluid and cover gasket, but I see conflicting info on what weight of gear oil to use. Manual states 75w-90 in both front and rear, but in researching procedure I’m seeing lots of people predict catastrophe if 75w-140 isn’t used in an LSD.

My first truck, so new to differentials. I lean toward following the manual, but since it’s an older model maybe experience has shown the heavier oil to be superior. On the other hand, people spout off with insufficient info all the time, and are maybe unaware that an “anti-slip” uses a different weight than other types of LSD.

Can anyone explain the discrepancy?

Thanks!

 

[Bigskyroadglide]

My 11, before I sold in had 75 140 rear and 75 90 in the front. I had 3.55s and LSD.

150k. No problems other than recall from at that time dodge because they didnt put a fill plug in the diff cover.

My current 14 RT has 3.92, I run 75 140 in it with LSD.

My 24 has 75 90 front and 75 140 rear, 3.92s.

I don't think you will hurt it. But if all else fails follow the manual.

 

[bcja]

Thank you that’s helpful.

I tried a different search and found this reddit link (https://www.reddit.com/r/ram_trucks/s/QRidGrbyqi). While generally helpful it makes it sound like the recommendations are all over the place.

It’s really my dad’s truck that he bought used. He never serviced any of the driveline fluids, and I have no idea what the previous history is. He can’t drive anymore and now I’m trying to rectify a lot of deferred maintenance so I can keep it on the road for a while as my vehicle. My teen son now drives my Sienna. The 1500 now has 145k or so on it.

I think I will go for the 75w140. Any thoughts on the need for the LSD additive?

Thanks again!

 

[Bigskyroadglide]

If it's got LSD buy the oil with the additive already included. It works as well as paying ma mopar for it.

If it's got LSD it needs the additive. I'd go full synthetic. Even super tech from Wally world will work but I'd probably buy a brand name. In a squeeze pak. You will need more than 1

 

[bcja]

Thanks, I was going to get a quality synthetic, I’ll see what’s available when I get to the store.

I’ve seen some people say that even if it says it has additive, you still need to add some. I’m not going to be making any warranty claims at this point, so I’ll probably put my trust in a reputable label. I have the capacities somewhere, I’ll get that and round up.

 

[bcja]

I discovered the issue with the discrepancy. The manual I found online a while ago was for "Ram Truck 2011", but evidently applied to Ram 3500/4500. Wish they'd have indicated that on the title page - or anywhere, really. I was getting my shopping list together when I realized some things were not adding up. Up until now it answered most of my questions about the truck so didn't have any suspicions.

I have now found the "Ram Truck 2011 1500/2500/3500" Owners Manual, and the rear diff is indeed 75W-140. They don't list capacities though, which is annoying. I'll find those.

Thanks again Bigskyroadglide, and sorry for sowing confusion. I feel like this is at least a little on Ram for not stating what the manual applied to, though...

 

[Daw14]

Little over two quarts.