Changing transmission fluid

CRAIG CJ HAUSE

MEMBER
1987 OLDSMOBILE 98
3.8L
6 CYL
FWD
AUTOMATIC
100,000 MILES

I have a 1998 Regency Brougham 3.8L. It is a California car, now owned by me in Michigan. When cold, the reverse is a little delayed. However, if I let the car warm up it is fine. The transmission fluid looks a little darker than clean engine oil. So it is a little dirty. I do not know if the fluid has ever been changed. I was told today by a mechanic not to change it (and filter) because it could cause more problems. The person said that "it is probably holding everything together". What should I do? I would like to change the fluid and filter. No other shifting issues. And even with the reverse, if I let the vehicle warm up, I would not even know that there was a delay when starting and immediately backing up cold.

1 Reply

CARADIODOC

MECHANIC
33,910 POSTS

The advice you got refers to flushing the system. It is believed debris will break off and get stuck in the valves or tear rubber lip seals on the pistons for the clutch packs. In my limited experience, a problem develops but it has not become really serious, yet. The flush is done with the thinking it is going to solve all the problems. When the problem gets worse, which it would have done anyway, the flush is blamed.

I worked with an instructor with no professional experience who believed material flaked off the fiber clutch plates, circulated with the fluid, and was needed to maintain the friction between the plates. He thought the flush would remove that material and result in slippage. In fact, if you talk with any transmission specialist, they will tell you any debris circulating with the fluid will either be caught in the filter, or it will tear the lip seals. The fact is a flush will not cause a slipping problem. The flush might fail to prevent the inevitable slipping problem.

A simple filter change is just going to remove debris trapped in the filter. That is not going to cause a problem.