So have 36k miles on the JK and getting things lubed and greased for EJS and thinking of doing fluid change in tranny (auto).

I've googled, yahooed and searched and seems to be split feelings on a tranny flush. To me it seems to make sense to squeeze all the old fluid out with new BUT people sure have some bad opinions of this....So I'm sitting here wondering DO I or DON'T I???? Any opinions. or just drop the pan with filter only???

 

I am not a mechanic but when I owned my jeep liberty I did extensive research on this issue and the consensus was that all you need to do is drain your fluid, replace filter and refill, no flush necessary.

 

I'm a tech for a living, on my personal vehicles I drop and change the filter and gasket only. I haven't had any issues. Flush would be more efficient but still aren't changing the filter. I would recommend one or the other, if not both. Any service on an auto is better than NO service. Thats for sure...

 

I'll throw in some more points to be considered while you make your decision.

Is your current fluid relatively "fresh" or is it "burnt" at all? The JK trannies are known to run hot for some folks or under certain conditions. If you don't (or haven't) run hot, than you fluid may be fine. Heat, more so than age/use, is the enemy of ATF. You may want a gauge to monitor your temps.

IIRC, a pan drain only removes about 1/3 of the fluid.

(If I remember my serial dilutions correctly, 7 drain & fills would theoretically replace about 94% of the original) ((2/3)^7) (it would take 12 to get over 99%, assuming perfect mixing)

(do a forum search for info on adding a drain plug to the pan for future drains and for info on temp gauges / OBDII gauges)

I understand there are different types of machines for flushing, I would avoid any that use a higher pressure to force out the fluid. They can loosen baked-on varnish that can then clog galleries leading to failure. Many an old timer will tell you about the tranny that was running just fine (even though the fluid was cooked) until after the flush!

My manual call for a "change" at 60K miles for taxi or towing, etc., or 120K miles otherwise.

What they mean by change...

 

seems to me if you have a lot of shavings that you wouldn't want to flush since (from what I've read) that the flush machines flush in reverse and sucks all the crap back through the tranny.....I think theres too much risk with a flush so I'm going with a pan drop....thanks for the replies by the way...