I replaced my 2004 Ram 3500 driveline fluids at 10K in 2010. The truck now has about 33K on it. So about 23K on the fluids. About 1/2 towing. The fluids have been in there 13 years. Is it time to replace them just based on the length of time they have been in?

They are Amsoil or Mobil 1 depending on the location.

 

Why not? Won't hurt anything.

 

Considering that you've been towing with it, I'd go ahead and do it.

 

I would change it. That's quite a long time for the fluids to be in there.

 

That is kind of what I thought too! Not sure why they would go bad but it does seem like a long time.

 

It's more of a thing to do for the peace of mind, plus you can see what the fluid is looking like.

 

Condensation will introduce moisture in your fluid over years, if you live in an environment with temperature swings. I'd just put some factory spec gear oil in there, since those rear ends will go 300K + miles with simple maint.