I have just passed the 20K mark on my truck, and was considering having the transmission serviced. I looked up interval in the owners manual and found the schedualed mileage to be at 100K ! I have always been told that you should service the transmission around the 25K mark? At that I looked in the heavy use schedual and it was at 50K? Are these good numbers to go by?

 

Things have changed with the new synthetic ATF+4 tranny fluid. If the fluid isn't burned, I believe it's best not to disturb the tranny any more than necessary. Note that synthetic tranny fluid doesn't stay cherry red for it's useful life. It'll get kinda pale but it won't smell burnt unless it is burnt. I've got 35,000 on my 47RE now and I tow heavy. The fluid still looks fairly cherry and smells good. I want to put my tranny temp sensor in the pan so I might change it out this weekend. Then I'll probably do it again at 50 just to stay with the plan...

 

read agin it is 30,000 miles fluid filter and bands

 

I was considering doing it every 25K and thats with light towing.

 

I better back up for about 5k miles and change it!
It's in that black book in the glove box...

 

I was planning on doing a tranny service @20k (and every 20K after), but the dealer ended up doing it at 10K with the C-44 (I think that was the number) recall on the trans cooler line. Ended up that the cooler on side of the engine block had blockage, so they ended up changing that too and doing the trans service.

Next service - 30K

 

Every 20K for me and the transfer case too.