ATF Flush or Drain and Fill? (170K legacy L)

[kellen]

My legacy is at 170k and I purchased at 130. 1993

There were no service records.. So I don't know if the transmission has ever been flushed. I'm hearing from some people that I shouldn't flush, that it can cause more problems than good. Some say do it...

 

Others say just drain and fill, maybe a couple times to clear out the old stuff..

 

Some say to have a shop flush, but not using chemicals..

 

Thanks in advance for the advice. I love this website!

 

Kellen

[xrturbo]

I would have it done with a flush machine with no chem. If you are having any issues at all there is an additive that we run with our machine: Lube Guard Shudder Fix. It comes in a tube.

[idosubaru]

fluid exchange is a great option, i'm with him. though i didn't know about the "don't use chemicals" stuff since i've only ever drain/refilled myself.

 

another option if your a DIY type is to have a huge container full of new fluid. have the intake hose pulling fluid from it, the other side hose going into an empty bucket. crank the engine over for a very short time. it will suck the new fluid up while dumping the old fluid out. when new fluid starts coming out, turn it off and you're done. i've yet to try that, but know others that have.

[nipper]

drain and fill 3x's is almost the same as a flush. Do the flush if you cant get rid of the old fluid easily or there are other issues. Do the drain and fill if money is an issue.

 

 

nipper

[OB99W]

This should give you an idea of what multiple ATF changes will accomplish:

http://www.ultimatesubaru.org/forum/showpost.php?p=621866

[bulwnkl]

I agree that for convenience or other related reasons you should take it to a shop and have them flush it. For $ or DIY satisfaction reasons do it yourself with drain and fill or cooler lines (if you have one). If you want to get gunk out SAFELY without any possibility of clogging things up, put some Auto-RX in first and follow the directions. I've done this on the A/T in our Baja with oustanding results.

[Rooster2]

I bought my 99 Legacy OBW about 6 months ago. I had no records on ATF change, but the fluid on the dip stick did not look dirty. Anyway, I changed the ATF 2 times, by simply running the car up on ramps, then pulling the drain plug on the bottom of the AT pan. It is a very easy "do it yourself" project, since the drain plug screws in and out just like the drain plug for the motor oil. Now, I know for sure that my trany fluid is new and fresh.

[OB99W]

Yes, the 4EAT has a drain in the pan, like the one for engine oil. However, while draining engine oil (and replacing the filter) changes the vast majority of the oil, doing that on the trans isn't nearly as efficient -- two changes via pan drain will result in about 64% fresh fluid (see the link in my post #5 above).

 

If the original ATF appears to be in reasonable condition (as apparently in Rooster2's case), two changes may be sufficient, but if the fluid is dark or smells even slightly "off", a complete flush or multiple changes is probably prudent.