1997 Silverado trans fluid change advice

[BrianF]

I had snagged an old 1993 1500, 5.7 with the 4L60E. I believe about 370,000km of hard use. Fluid was dark, very dark but did not smell burnt. It had a 3-4 shift flare, a shutter when in lockup under light load under 2000rpm and it slipped bad when trying to pass on the highway and not in lockup. In fact, you couldnt accelerate to pass unless it was locked. Likely the original fluid.

I did nothing more than a fluid exchange via the cooler lines. I used some cheap Dex/Merc in it and not even a filter . After a few miles it almost ran like a top. The only issue is the shift flare remained.

 

[clinebarger]

On the 4L60 I personally don't replace the filter seal unless it's obviously bad. Maybe that makes me a hack but IMO you're more likely to do damage trying to get it out or drive a new one in. Maybe there's a specialty puller kinda like the one for the shifter shaft seal?

The 1/2" NPT tap with a nut welded on for a slide hammer works very well to extract the seal, The problem is trying to convey how tight to run the tap into the seal & knock it out the first time.....Goal is not to expand the steel shell into the aluminum bore, But still grab onto the steel.

But....Like you said, If the seal holds a filter it's best left alone.

 

[LDM]

I've done fluid changes and a few seal replacements on my brothers 97 K1500 for the 4L60E, has over 250K on it these days. I've used both MaxLife and Supertech Dex/Mec with no issues. As long as its a good Dex/Mec or Dex6 fluid I don't think the fluid will be the issue. Abuse and neglect kills more of these transmissions than anything else.