1997 vortec 5.7L tranny oil change

[mbecke2]

I have 2wd 350 full size with 143,000 and I would like to change the tranny oil. I've never had it done before and the oil looks black. Ive read and heard many horror stories about blowing the transmission by not changing the ATF correctly. Should I bring it to a mechanic or do it myself?? Where do I start?? Is it fairly easy?? The tranny works fine but it shifts slightly hard into 2nd and 3rd, but not real hard. I certainly don't want to blow the tranny. Should i leave it alone??

[jdmccright]

The horror story you refer to is that most people in here will recommend that you NOT flush the transmission, especially after running it wayyyy past a scheduled change. But most drain & fill changes only change about 1/2 the fluid. In your case with the 4L60E, you have to remove the pan to drain it, so you can change the filter inside as well as clean off the particulate magnet on the inside of the pan.

If you're a DIYer, (and presuming you have the 4L60E transmission) the o-ring seal for the new filter is a PITA to remove if it has been driven all the way into the valve body. I've had luck with using one of the jaws of a pulley puller as a big hook with a screwdriver slid through one of the holes as a handle to grip with both hands. Make sure the truck is securely on jack stands and wheels chock-blocked...and pull down with all your might. At minimum you'll dislodge it enough to be able to collapse it with a screwdriver and hammer. Once removed, drive the new one in with a socket but leave the lip of it slightly extended below the valve body's hole so that you can remove it by collapsing it...without all the massive yanking. If it doesn't have one, think about installing a drain plug in the pan.

Reinstall the filter, pan, and refill. Run it for a few hundred miles, then drain & refill again. Run another few hundred and drain & refill again. Yes, it sounds bothersome and wasteful, but the deposits that have built-up inside the valves and passages are slowly dissolved this way, rather than them breaking off during a high-pressure flush and causing a blockage more critical elsewhere. Two changes is good, three is better.

If the symptoms still exist, an option after the last drain is to substitute some tranny additive like Lucas Transmission Fix to help stop internal leaks and smooth out rough shifts. Use as directed on bottle...DO NOT OVERFILL.

Except for the filter o-ring, it's not a difficult job, but it can be time-consuming the first time...and messy. Have a drain pan and towels ready in case you miss while cracking open the pan (as mentioned above you have to loosen the bolts to drain it)...loosen a little at a time and be patient while letting it drain out. Good luck!