Just curious if there’s anyone with high miles on original transmission fluid. I just picked up a 99 gs400 130k and it seems the transmission fluid was never changed looking at service records but the car drives great. Just wondering if it’s even necessary.

 

Fluid is the life-blood of the transmission, like oil is to the engine. It can't hurt anything and is super easy to do. Do it after a short drive so everything is warm, but it doesn't need to be hot.

There is a drain plug in the bottom of the trans pan. You will not get it all out of course, but if you do it twice a few hundred miles apart, you'll replace about half.

I used a MightyVac through the fill tube and was able to get just a little bit short of three quarts out each time.

Make sure you use the correct spec fluid when replacing.

 

I would definitely suggest doing a drain and full of the fluid. Not a flush as that can cause problems. But you need to get good fluid in there.

 

Changing the tranny fluid is much easier than a messy oil change. Just drain and refill every oil change to introduce fresh oil, then extend. I drain and refill every 40k (3 quarts).

 

It was at about 130k that I had to change the oil because I was getting a slip into 2nd gear when the engine was cold.

 

Thanks everyone. At first I wasn’t sure if it was ever changed so didn’t know if it was bad to do it for the first time at 130k. However I found hand written service records and it seems he changed the transmission fluid along with the rear differential fluid so I will continue to do that every 30k or so

 

I would just drain the oil pan, measure what you got and refill. Then remove one line from the oil cooler, put it in a drain bucket, have a second person start the engine and as soon as bubbles come from the line, shut it off. then measure and refill again. this way you get the whole system flushed quicker. repeat 1-3x. after that check level on dipstick.