My 07 just hit 60k miles, and I'd like to change all the fluids in the diffs, transmission and transfer case. Has anyone done this that could provide any insight? I'm not sure if or when it has been done, I bought it with 52k on it. Also, when I try to use the rear locker, the "Service 4WD" message flashes on the dash. Any ideas? I don't have a manual for the truck, so what other things need to be done at this mileage? Thanks in advance!

 

First off, you can download the manual for free. I don't have the URL, but use the search function on this forum & you'll find it.

The manual calls for changing the transfer case fluid at 50K, transmission at 50K for severe service 100K for normal service. It doesn't call out a specific mileage for the diff's, but the consensus seems to be that 50K is a good idea.

I just changed the fluids in both diff's last weekend. Took about an hour and 4 qts of 75W90 Synthetic - I used Royal Purple for about $18 per quart. I highly recommend a hand pump for filling - got one at Advance Auto parts for $6. OBTW, the stuff really does smell so be careful of spilling it on anything.

The local dealership wanted $139 each to change the diff's. I can't understand that when they do an oil & filter change for $39.

 

First off, you can download the manual for free. I don't have the URL, but use the search function on this forum & you'll find it.

The manual calls for changing the transfer case fluid at 50K, transmission at 50K for severe service 100K for normal service. It doesn't call out a specific mileage for the diff's, but the consensus seems to be that 50K is a good idea.

I just changed the fluids in both diff's last weekend. Took about an hour and 4 qts of 75W90 Synthetic - I used Royal Purple for about $18 per quart. I highly recommend a hand pump for filling - got one at Advance Auto parts for $6. OBTW, the stuff really does smell so be careful of spilling it on anything.

The local dealership wanted $139 each to change the diff's. I can't understand that when they do an oil & filter change for $39.

 

Try checking the locker wiring at the rear diff for the service 4Wd message. If that circuit is broken (ie the wires could be unplugged) it will cause it to throw that message. There is a plug on the top drivers side of the rear diff (right near the rear of the fuel tank) with two wires going in/coming out, that's the one you're looking for. There could also be other things that would cause it to give that message, probably tied to the locker circuit if that is the only time it gives that message.

 

Thanks for the info everyone, I really appreciate it! Should I pull the covers off of the diffs to clean them out when I change the oil? Does anyone know the process for changing the transmission and transfer case as well? I'll check the wires to the diff when I'm under there, thanks!

 

I don't think that it is necessary to pull the covers and clean inside the diffs when you change the oil, although it shouldn't hurt anything if you do it right. If you only knew how many diffs ther are out there that have gone hundreds of thousands of miles without the gear lube ever being changed you'd be surprised.

I'm pretty sure on the tranny that you need to drop the pan to drain the oil, (which usually results in a huge mess). On most auto's it's pretty hard to drain out more than about 70% of the old oil, so it's not a bad idea to take it to a shop that can suck it out. I'm not sure how they do it but they claim to get all of the old oil out, it's probably worth it if you really want a good job done.

Transfer case should have a drain plug down near the bottom and a fill plug about 2/3's of the way up, on some of the early t-cases there was a special fill procedure because the fill plug was to low so you had to add gear lube through the speedo cable hole to top it off. I don't know when they changed that.