Hey guys I got a 99 4runner and i noticed the trans oil was really dark (like dark enough that i would believe that it has never been changed), didnt seem to smelll just pretty damm dark....so i drained it and filled now the color is much better but i just started reading other peoples posts about flushing the trans and got to thinking maybe i should do that instead, the truck has 75k miles on it....do you guys think that flushing it might cause problems since there might be a chance that the trans oil was never changed before?

Thanks

 

Draining and refilling the A/T only changes ~3 of 12 - 13 quarts of ATF. The rest resides in the torque converter, which has no drain plug.

The good thing to do is a complete ATF fluid exchange. This isn't cheap (c. $135 using Mobil 1 synthetic ATF), but your tranny will love you for it.

I did this @ 30K miles with my '98, and never had a single tranny problem despite towing a 4,000# trailer.

Regards.

 

You could also just change the fluid several times to get the majority of the bad stuff out. Drain it, add two quarts, drive for a week and repeat. Do that 4 or 5 times and you have a poor mans tranny flush.

 

it is quite possible to do it yourself, if I recall someone did a write up of a DIY trans flush at home.

 

Thanks for the replies....I ended up doing the trans flush pull-off-the-left-a/t oil-cooler-line flush as per a bunch of DIY stuff i found on YT...I was mostly worried that since the trans oil was so dark that by doing a flush I would clean out the varnish and crap and get it stuck somewhere in the trans....but i figured if the trans is going to die then damm it die with good oil...so 15-16quarts latter its all nice and light red...only put on about 100 miles or so since i only drive it on weekends but so far trans is working just fine.