Diff/trans gear oil change interval.

[LWDUPPONG]

I have 90,000 on my 03 and have never changed the diff oil. I noticed in the owners manual that it should have been changed twice by now. I would like to switch to synthetic in both trans and diff.



I put on a lot of miles (60,000 since March). Some trailer towing w/car on and/or truck box full of semi parts.



How often do others change these fluids?

 

[LRutigliano]

Stock fluid is synthetic (75W-90).



I change mine approx every 15k just like the owners manual recommends.



I run RP 75W-140 in the rear and RP 75W-90 in the front. When Amsoil finally figures out that gear oil should come in the universal tall skinny gear oil bottle with the easy pour cap, I'll switch to their extreme gear oil...



With my PML covers, changing the fluid is super easy and no mess...



I tow with my truck approx 90-95% of the time, so I keep my intervals at the 15K recommendation.



Hope this helps,

Louis

 

[LWDUPPONG]

Thanks Louis.



I'll check into the RP at NAPA. Have you done any fluid sampling on your diffs to check for wear?

 

[LRutigliano]

Thanks Louis.



I'll check into the RP at NAPA. Have you done any fluid sampling on your diffs to check for wear?

No, I haven't done sampling. I see it as very cheap insurance to change every 15K and with the cast alum covers, draining and refilling is as easy as changing your engine oil.

 

[steved]

I think you will find a good portion here don't follow that almost crazy 15k change interval... its pretty excessive since most gear oils are fairly durable. I would probably consider a 75w140 over the 75w90 as the general feeling is the 75w90 was to meet CAFE numbers, and not really for durability. I believe at least one dodge dealer recommends 75w140 for those that do tow...

I changed at 50k and again at 90k (when I added a aluminum cover). I have seen zero metal on any of the magnets. I have 170k on currently. I have been running 85w140 RP since 90k... it has served me well.

I believe if I remember correctly, the severe service is 15k and the regular service is not specified... but its been a while.

 

[AH64ID]

I spoke with AAM 10 days ago and asked several questions, one was why was a 75w-90 recommended over the 75w-140 for a HD axle. They said that under 99% of circumstances that the 90 outperformed the 140. The only time the 140 was better was towing at GCWR thru death valley, or death valley like temps. So I would think that 75w-90 is still the best choice, but if you want a little more go with the Amsoil 75w-110.

For me I run the Amsoil 75w-90 and will change it at 50K intervals.

 

[mberry]

I change my diffs and trans at 30K miles. Trans case at 15K miles. I use Amsoil 75W-90 but have used RP on several occasions.

 

[AH64ID]

I change my diffs and trans at 30K miles. Trans case at 15K miles. I use Amsoil 75W-90 but have used RP on several occasions.

Out of curiosity, why change the xcase at a shorter interval? It sees the least wear.

 

[Dave04]

Where can I get Amsoil at and is there any other I can use that I can get at like auto zone or some where local? Thanks

 

[DPKetchum]

AMSOIL - Synthetic Oil, Motor and Engine Oil, Lubricants, Air Filters, Oil Filters and Greases

 

[cruiser_2]

Well I guess I must be a fool because i didn't change mine until almost 430,000 miles. Oil was a bit dark, but analysis showed viscosity and lubricity within usable limits... some increased iron and fobrous particulate. I used RP when I changed and have had very good service... now almost 509,000 miles.

 

[steved]

... i didn't change mine until almost 430,000 miles.



... now almost 509,000 miles.

I just hope my truck will even last that long... :-laf

 

[mberry]

Out of curiosity, why change the xcase at a shorter interval? It sees the least wear.

I believe it has been discussed before, but mostly because it turns all the time regardless of whether or not you are in 4X or 2X, and has the least amount of lube capacity for drivetrain components. In fact now that I think about it, it's overdue for a change.

Every time I have changed it, what came out was brown and just nasty looking. I know color doesn't indicate whether the oil is bad or not, but it makes me feel better and is in line with my owners manual for maintenance interval.

Hope that explains it for you.

 

[DPKetchum]

What is the maintenance interval on the transfer case?

 

[AH64ID]

30K mile check interval, on schedule A and B; change is 60K for schedule B, and no scheduled change on A. Diffs are 15K for schedule B, and no scheduled change for schedule A.

Yes the xcase is always spinning, but there is no gear reduction, or multipile gears spinning, so you don't get the friction of a transmission or diff. It just passes power thru.