jfmorris

I've got a 1996 C1500 5.0L with the 4L60E transmission. In 2009, at 100,000 miles, I had the transmission filter and fluid changed. I kinda did it as panicked preventative maintenance after my 2003 Yukon transmission had to be rebuilt at 130K miles.

Anyway, it is now 2024, and the 1996 C1500 has recently rolled over 200,000 miles, currently sitting at 201750. I am ordering new spark plugs and wires from Rockauto, and I am pondering the wisdom of flushing the transmission again. I've read more online in recent years about transmission failures caused by changing out the fluid, as the detergents in the new fluid supposedly break free deposits that can cause the transmission to then fail. Knowing what I know today, I probably should have been thinking about transmission fluid much more often than 100K miles, but its a pain to do yourself when there is no drain plug, and you have part of the frame blocking dropping the pan...

Any thoughts or wisdom from you guys (and gals) here as to what needs to happen here? Should I drop the pan, change the fluid and filter, flush it, or leave it alone at that age and mileage? My son in law had a 2004 Silverado with 260,000 miles on it and a transmission shop refused to flush it, as they claimed it would cause a failure - but he was on the original fluid. I changed it once, 100,000 miles ago on this truck.

Thanks!

Rednucleus

At 200k w/o a rebuild you have done better than most. Unfortunately, 100k since last service not so good for your tranny's future. A full flush and fluid change now may do more harm than good. Drop the pan and fluid & filter probably ok, but at 200K it has had a full life. Years ago we had our 93 Sub 4L60E full flush at 200k; fluid/filter had been changed two times previously. 20k miles later it was dead. Coincidence?