Trans fluid change on my 2007 suburban with 320,000 miles.

[MARK_VANDERBENT]

I bought a high mile suburban and the as far as I know it's the original trans, and I have no idea when the fluid was changed last. It is pretty dark but not burned. The truck shifts perfect and shows no signs of a problem. I have heard don't touch it, because new fluid may shock it into problems. I want to introduce a bit of Lucus, but fear this may clean out and dislodge sludge. What you all think?? Change it? Or. Leave it alone? Oh and yes I tow a trailer with this truck.

[coolmom42]

General advice I've heard is to drain it and refill with new fluid, as opposed to a flush. Depending on the vehicle, you will get about 1/3 of the fluid or more. Do this a few times in a short time span and you will have mostly new fluid. This doesn't disturb wear particles like a flush will.