i plan on changing the oil and filter after winter in my 2001 jimmy(and maybe the 98),,,how do you remove the filter gasket/seal or do you just leave it ..like i 've done the last two times and what about any additives,,?

 

I've done this. As you know, the cross member is a pain to work around. My GM service manual calls for a new pan gasket to be installed with each removal.

The problem is that when you can drop the pan you get less than half of the ATF out; only 5 out of the total of 11 qt. That is why I bit the bullet and have a local transmission shop replace the filter and do a flush to replace all the fluid. They don't add any additives but they do use full synthetic ATF.

 

More than a few shops will tell you NOT to get a flush on a higher mileage tranny. After I had mine rebuilt with 25K miles on it I went in to get a flush. The shop supe told me I shouldn't until I told him it had the 25K on the rebuild. Ever since that flush I've don the drain and fill. Seems a flush on a higher mileage engine may cause slipping and/or burning of the clutch packs. Once the weather warms up, as in May, I need to drop the pan and do it again. And by all means, use a new gasket!

 

not a gasket,but a seal for the filter...i did do a flush years ago on a 98 blazer...they did it correctly,unhooking the trans lines off radiator...did another on probably the 98 jimmy,quick lube place,i know they only stuck something down the dip stick hole and sucked it out,,BS,,both these were dpne after i changed the filter and cleaned out the pan

 

Right or wrong, I did a tranny flush, the vehicle had about 265,000 km.

This was done by unhooking the lines off the radiator like Int3414 says above. I cut a line from the autowreckers to make a spout or a nipple, and then attached a hose to a bucket. If I recall correctly it took about 16 or maybe 18 quarts before the fluid ran clean.

Even though it may not be recommended, I feel better having clean new synthetic fluid. And lucky for me it hasn't seemed to cause any problems (yet), the vehicle now has 280,000 km.

 

That kind of flush isn't going to hurt anything. When one brings in a vehicle to a shop they do a power flush as the fluid is pumped int under pressure. This is the kind that may cause the clutch packs to start slipping.