I have about 16500 mi on my 05 LLY, I have followed recommended trans. filter change and rear end fluid change schedule. I did 2600 miles of trailer towing over the winter and have just purchased a new fifth wheel camper that puts me close to my pay load limit and will be taking a long trip with it in July. I was thinking of changing the rear end fluid again and changing the trans fluid early. Am I wasting my money? My dealer thinks so. Any advice helpfull.

If it makes you feel better......go for it. When did you change all the fluids originaly or the last time? If it was at a 7500 mile interval then the oil, tranny and fuel filter should be changed. If the diff was changed at 2600 miles, you should still be good to go.

If you do decide to change your trans fluid early you should switch to Allison Transynd. I would wait to change the fluid till I was around 25k but it sure wouldn't hurt to change the spin on allison filter. Just my 2cents.

You should do what ever will put your mind at ease. If the money isn't a problem I probably would change it. Can't hurt.

Thanks for the come back, I think I'll go for the trans filter change and leave the rear end fluid.I was going to have the 25,000 mi trans fluid change at a local Allison center,I will ask for the Allison Transynd. I have done the fuel filter twice and change the engine oil @ 5000 mi intervals using Mobil Delvac. The rear end was done @ 5000 mi.I just thought freash blood for the beast before I beat her would be in order.

I did all the fluids, - engine - ( Delvac 1) ,front, rear, tranfer ( mobil 1 ) , and tranny with (Transynd) at 1000 miles and am glad I did. The front end comes out like milk, plus GM is known for low fluids from the factory. You will put in way more than you took out.
Just knowing I have premium fluids makes me feel better, and the truck run cooler.

I'll ditto what Kendall69 says. At 10K mark, I change out the front, rear, and transfer oil. Rear one was low and front was milky color. After reading post on this forum, I just concluded it was a good move. Happy Trails!!

I'm ready to do this also. Is the transfer ATF? Only took about 2 quarts out of the rear diff - put 3+ back in.

I have about 16500 mi on my 05 LLY, I have followed recommended trans. filter change and rear end fluid change schedule. I did 2600 miles of trailer towing over the winter and have just purchased a new fifth wheel camper that puts me close to my pay load limit and will be taking a long trip with it in July. I was thinking of changing the rear end fluid again and changing the trans fluid early. Am I wasting my money? My dealer thinks so. Any advice helpfull.

With summer coming on and as hot as these trucks run, I don't think you can change the fluids often enough.

typo.

I'm ready to do this also. Is the transfer ATF? Only took about 2 quarts out of the rear diff - put 3+ back in.

IIRC, 2 qts of ATF in the transfer and 4 qts of GL-5 in the rear diff.