Look, my experience with transmissions is ltd at best. But I have had about every issue a person can have. We have a 1993 88 with 165K. Car runs like a dream. But, it literally has to warm up 10-15 mins before D or R will engage. Once its going, shifts like butter. No slips, no problems with hills, etc. Have changed fluid and filter. The only relief we got was using Lucas in it which worked great for a few weeks. Then back to square 1. I am thinking the T.C. is either gummed up, has a bad seal, etc. Or the pressure solenoid is going. Really could use some ideas.

Sometimes it is just best to pull the trans & have it rebuilt. That being said, the valve bodies,accumulator & Solenoids are subject to gumming up with varnish. This can cause shift issues. You can try adding a can of sea foam Trans Tune to remove the varnish and drive it on the highway for a few hours run & see if when cold it improves or not.
Link to Trans Tune: Trans Tune - Sea Foam Sales Company
On a level surface after driving for 30 min or more in (cold outside temps) running in Park, check to ensure your trans fluid is slightly above the full line on dipstick. When cold you may not have enough fluid as well?
Did you use the latest GM fluid Dexron VI (6) when you changed the filter & fluid?

I have the same problem with an '91 Olds 98. BUT the problem only occurs when outside temps are cold..... it started doing this again a week or two ago.... BUT has not done it since early March. When you first start car and put it in gear, it does not move BUT if you allow it to run for about a minute then put it back in gear, it works fine... until car is completely cold again (ie..... sit all day at work in parking lot)........ I'm assuming a similar issue..... as I don't have to wait a long time....only a minute or 2 before it moves fine.

Just about when I posted this, I tried Lucas trans treatment. Really didn't do much. Then I put a bottle of Seafoam Trans tune in and this thing will (almost) instantly go into gear-like a couple min warm up opposed to 20 mins. So we will see how long this lasts. Thanks for the replies!!

If it is shifting better with the Sea Foam trans tune, that is good news.
Take it for a good hwy run and check your fluid levels.
I would consider in the future servicing the trans again (check for any particles in pan)
and use the new synthetic Dexron VI fluid, and add one more bottle of Trans Tune to really help to clean things up!
Good luck let us know how it'* working out!!

since older and longer miles

whata bout using an atf fbrand meant for high mileage-older cars(dex3ish) than dex6?

Dex 6 Supersedes all of the other older Dexron fluids and is a much better synthetic fluid, able to handle higher temperatures, with better cleaning properties.
Here are some of the advantages of Dexron VI.
Extended fluid life,Improved oxidation and thermal stability
Optimized frictional properties that provide smooth gear shifting during low temperature operation and help prevent transmission vibration
Outstanding resistance against sludge and deposit formation
Improved anti-wear protection which contributes to extended transmission life
Outstanding low temperature performance. (much better in the cold it is synthetic)
I use Mobil 1 Dexron VI . There are many approved brands to choose from.
DEXRONŽ-VI

Thanks ^


have ya or anyone had any issues mixing dex6 with a car originally/replenished with dex3/similar ?