A) You will probably have a non-functional transmission soon after doing this. Good luck. I would just leave it.

B) DO NOT (even more so especially in this case) use synthetic ATF in the 4L60E, it's too slippery. With factory clutches, Dexron III is all you need.

 

how would changing the fluid/filter hurt my transmission?

 

if it aint broke, don't fix it lol

 

Trying not to hijack the thread here, but my 2000 silverado ecsb 6.0l has 113k miles on it and has towing package so the deep oil pan and tranny cooler. I was going to do some transmission work (change to corvette 1-2 servo, billet 3-4 servo, transgo shift kit, transgo separator plate, 1-2 aluminum accumulator piston and forward clutch accumulator piston).... and I was planning on changing the fluid and filter at the same time. So will that ruin my transmission as well? Should I change the items I was wanting to change above and dump the old stuff back in and leave the old filter in place? I would like to have a better performing transmission, hence the reason to do some upgrades and maintenance, but will I just end up killing my transmission in the same manner you are telling Shane?

 

I think that the idea that was brought up here is that if it has never been serviced, it is not a good idea. If the fluid does not look good or is dirty it could damage your transmission. The idea is that as these things wear they create dirt. ATF being a detergent, it will start to remove dirt from the transmissions internal parts and friction material. When this happens it will increase clearances in the transmission clutch packs and also the clutches might not take well to the new fluid. When this happens they can disintegrate or flake apart causing the trans to start slipping. I hope this better explains as to why the advise above was given. Vince

 

Happened to me! Very soon after I changed my fluid and filter I figured the truck had 90k on the clock and it could use a good refresher on fluids and what not.... oops!

 

Yeah, Vince nailed it. In most cases, when the fluid is that old, replacing it with fresh fluid will eat some clutches. It doesn't "hurt" your tranny, just hurts your wallet when you have to pay for a rebuild sooner than if you had just left it.

 

Here's my experience:

I did the same upgrades you're planning a couple years ago with about 70k on the clock. Changed the fluid and filter when I did them. No problems for a couple years. Decided to drain the pan and add some fresh fluid around 88k.

To my knowledge, the fluid had only been changed twice before. I did it at 50k and as said above, 70k.

The fluid I drained looked clean and new, but later that week, I lost 1st gear. I should have just paid for new clutches and a rebuild at that time 2 years ago, and probably would never have had that trouble. Because realistically, how many guys here have a factory 4L60E lasting more than 150k anyways? You gotta figure that those clutches are at least 2/3 of their way to death already. In my case, I think the old clutches were unhappy with the new fluid.

 

From what Im told by friends who build all kinds of trans for people, is if u beat it, change the fluid about every 15k, if not every 30k, if you dont change it b4 70 or 80k dont do it. thats what ive been told.

 

I wouldnt change it with that many miles on it. I change mine once a year, which in my case still isnt very many miles. 5K maybe a year on mine. Now less since I got a DD.