Change trans fluid or no?

[kennythewelder]

I changed the fluid and filter on mine at approximately 200k. About a month after I lost second and OD. $2000 later I had a rebuilt transmission.

This is why I don't change mine. 231,000 miles, and still going strong, but I did do a flash tune on it around 200,000 miles or so. I used a Jet programmer on mine, but a custom tune is more effective, although my shift points are much sharper than OE.

 

[BowtieBrody]

Planning on adding a Mag-Hytec pan and an upgraded cooler, maybe a shift-kit; not sure yet.
Would the extra fluid from the increased pan size help it? My fluid is dark although smells fine, just want to try and beef up my trans and get all the maintenance gone through. My truck is similar to OP's; 96 K2500, 454/4L80E, 147,450 or so as of tonight.

 

[Justin S]

I used to have a 1972 Chevelle with a TH350, just about 99000 miles. I did a pan drop and filter change just because it was brown, and within 2 weeks the trans stopped shifting into 3rd when warm. Since then I haven't changed fluid unless I had a reason to, like install a shift kit or gasket change.

 

[Rparsh]

How does the fluid in there now look? If it's still clear and red/pink a drain and fill probably wouldn't hurt anything but if it is brown/black and hazy then there is clutch material in the fluid itself which is why they start slipping if changed. The material in the fluid provides extra friction to the likely worn clutches and removing it with fresh fluid reduces friction and can cause slipping.

I have a spare car unnamed and front wheel drive that I used to drive to work and back 28 miles total a day. Coming home at night I would feel a shudder going up hills. The alternator went out on it and it was a 4 hour job to replace it. Up on jack stands, pull the right front drive axle and the bolts that held it in went in from the inside out. I reached over and got a drop of ATF on my finger and smelled it. Smelled like burnt Lousianne coffee with chicory. I drained it out and what a smell. Got about 6 quarts out of it. No replaceable filter. Replaced with new fluid and the shudder went away and 10,000 miles later it is still fine. This Mercury Mystique has 270,000 miles on it and still runs fine. I have heard the story about don`t service the trans also but have no faith in it. If it is that far gone it needs to be rebuilt because one day it will leave you stranded.