Differential Fluid Change Intervals

[Grizzly]

The owners manual say to change the front and rear differential fluid every 30K interval. Isn't that too often? What's the best fluid to use?

 

[Regcabguy]

With my camper weight and a stock cover,my factory fluid was darn near as black as my engine oil. I added a Mag-Hytec and Amsoil 75-90 Severe Gear@9,000 miles.

 

[mberry]

I change mine every 30K miles. I have used both Royal Purple and (currently) Amsoil 75W-90. I have been happy with both fluids.

 

[JCleary]

I changed mine out at 15k. The stuff that came out was nasty!



Hopefully the Amsoil I put in will fare better...



On my '03 I changed every 15k. Made me feel better about beating on it.

 

[LRutigliano]

I believe if you tow heavy (schedule B), then the interval is every 15k.



Mine was dark and I also noticed the paint would flake right off of the cover after a heavy tow. I painted it a few times.



I then realized it was getting hot. I did a search and found that the stock diffs do run pretty hot when towing.



I got the PML covers for the front and rear. The rear adds approx 1 additional quart of fluid. I talked to the service manager at the local Dodge dealership and he recommended I run 75W-140 in the rear. He has a 2006 Mega Cab and a 5er similar to mine and he uses 75W-140 in the rear too.



I strongly considered the Mag-Hytec covers, but they stick out alot because of their capacity and I was worried my spare tire would contact the cover when my rear suspension drops with the 5er on it. Also, I didn't like being a billboard for Mag-Hytec (they have a huge label on their covers)... the PML have no label and looked nicer to me...



I use Royal Purple because its available at the local sports store and it comes with the right bottle that allows you to simply pour into the diff cover hole. I would use Amsoil, but it comes in a goofy bottle that requires you to pump it in or buy a special flexible adapter.



My intervals will be every 10k to match the trans... the local trans shop recommended I change out the trans fluid every 10k instead of every 30k. With the cast alum covers with a drain plug, the drain and fill only takes minimal time to complete...



I have pics in my photo gallery if interested.



Hope this helps,

Louis

 

[DE Jeeper]

Call me crazy, but I change at 50k. I tow a good bit and still have not seen fluid color issues. I have used Mobil 1 and other off the shelf synth 75-90.





Aaron

 

[MA2LA]

i was late on my first change at 55k and i just changed it again tonight at 98k. This time I used RP 75-90 and put on a mag cover. Last time i used some normal walmart gear lube with lucas treatment and it looked very good wwhen I drained it and that has been with more power and hard pulling.

 

[SBeretz]

Me too, I hit my diffs up every 50K. I used Mobil One 75/140 in the rear and 75/90 for the fronts. I pull pretty heavy when I do pull, so I would hope the 75/140 helps out in that regard. I may add some larger diff covers the next time. Scotty

 

[AABEN]

I change at every 25000 all so change transmission / transfer case I change oil and oil filter and fuel and air at 6000 miles oil is cheeper than repair bills.

 

[2broke2smoke]

first change at 30k looked like honey ...



now at 56k it looks clear on my finger so i'll check it again at 75k

 

[Grizzly]

Thank you everyone for all the good replies. Sounds like 30K interval is the best and safer, however if I should forget, I can go a little longer. I'm going to use Royal Purple 75W-140 because I can do it myself as LRutigliano said. Beats paying the dealer to do the changes. I'm a little confused about changing the covers. What the the advantage and what's wrong with the covers that came with the truck?

 

[Regcabguy]

Thank you everyone for all the good replies. Sounds like 30K interval is the best and safer, however if I should forget, I can go a little longer. I'm going to use Royal Purple 75W-140 because I can do it myself as LRutigliano said. Beats paying the dealer to do the changes. I'm a little confused about changing the covers. What the the advantage and what's wrong with the covers that came with the truck?

The aftermarket covers(especially the Mag-Hytec) increase capacity thus lowering temp. There's nothing wrong with the stockers and the gaskets are reusable.

 

[LRutigliano]

Thank you everyone for all the good replies. Sounds like 30K interval is the best and safer, however if I should forget, I can go a little longer. I'm going to use Royal Purple 75W-140 because I can do it myself as LRutigliano said. Beats paying the dealer to do the changes. I'm a little confused about changing the covers. What the the advantage and what's wrong with the covers that came with the truck?

Main advantage for me is the magnetic drain plug. I don't need to remove the entire cover to change the fluid. Also, if I do need to remove the cover for some reason, I can drain it first and not make a huge mess.



2nd advantage is the increased capacity and cooling fins to keep the temps lower.



3rd advantage is it looks much nicer than the stock one, especially when the paint peeled off.



Our trucks come with very nice overmolded gaskets that can re-used many times, so the installation is very easy. (no RTV to mess with)



Hope this helps,

Louis

 

[Wingate]

Changed mine at 15,000, looked terrible and smelled even worse. Installed a Mag Hytec diff cover and Valvoline 75/140 synthetic. Going to check it at 30,000. If it looks good, it will probably be 50,000 before I change it again.

I had actually monitored differential temps. before I changed the oil and cover. The way I did it was with a temperature tape, at one point during the "winter" here in Texas, it got up to 280 degrees on the cover. The next morning, I called Geno's and ordered my cover.

I put a temp tape on the front of the pumpkin close to the pinion bearing, haven't seen above 180 degrees since.

 

[Dave04]

How hard is it to change front and rear diff fluid? What do I need to do to change it? Is flush needed or just drain and fill? What are capacitys?

 

[LRutigliano]

How hard is it to change front and rear diff fluid? What do I need to do to change it? Is flush needed or just drain and fill? What are capacitys?

It is very easy.



All you need to change it is a 13mm socket and a torque wrench. The gasket is very high quality (rubber overmolded over a steel spine) and is reusable.



No need to flush, just drain it by removing the cover.



Torque in the Dodge SM is 30 ft-lbs, but I would go with 20 ft-lbs or 25 ft-lbs at the absolute max as they are 8mm bolts on the stamped steel cover and if you break one, then you have to get it out.



Front capacity is approx 3. 25 qts. Rear capacity is approx 4 qts. Both front and rear use 75W-90 synthetic gear oil. I use 75W-140 in the rear because I tow heavy 100% of the truck usage. You add oil in the pipe plug hole near the middle of the cover, until the oil comes out of the fill hole.



I usually paint my covers with flat black or semi-gloss paint, before I bought the PML cast aluminum covers which you can see in photo gallery...



Good luck!

 

[THoltz]

Thank you everyone for all the good replies. Sounds like 30K interval is the best and safer, however if I should forget, I can go a little longer. I'm going to use Royal Purple 75W-140 because I can do it myself as LRutigliano said. Beats paying the dealer to do the changes. I'm a little confused about changing the covers. What the the advantage and what's wrong with the covers that came with the truck?

Advantages:

larger capacity

improved heat removal over standard cover due to larger heat transfer area

drain plug

dip stick w/ O-ring for sealing

pre drilled/tapped 1/8" NPT thermocouple port

no gasket to replace if yo want to remove cover to inspect, it has an O-ring

 

[THoltz]

Changed mine at 15,000, looked terrible and smelled even worse. Installed a Mag Hytec diff cover and Valvoline 75/140 synthetic. Going to check it at 30,000. If it looks good, it will probably be 50,000 before I change it again.

I had actually monitored differential temps. before I changed the oil and cover. The way I did it was with a temperature tape, at one point during the "winter" here in Texas, it got up to 280 degrees on the cover. The next morning, I called Geno's and ordered my cover.

I put a temp tape on the front of the pumpkin close to the pinion bearing, haven't seen above 180 degrees since.

Where do you get the temperature tape?

 

[cruiser_2]

I know I am just a little bit over the top, but I changed mine at 450,000. was a bit dark, still have a sample to send into for analysis just for fun.

 

[cojhl2]

I changed mine somewhere between 300 and 500k. Hard to tell casue the speedo was broken for about 2 years.



In my opinion changing gearbox oil is a waste of time. What is there to polute the oil? (and if you see filings it is too late anyway)



On a big truck which works the gearboxes a lot harder than we do, if they changed so often they would always be in the shop.



Now the auto tran is a different story. It has clutches that slip etc.