5eat tranny flush/ fill or drain /fill

[peril]

Hey all - I'm considering doing a drain and fill or a flush and fill; anyone have any opinions on which is better. Car is a 3.6 ~155k miles. what is the flow direction of the tranmission cooler so in case I want to drain that I pick the right one and don't make a mess.

Any fluid recs? 

Appreciate your help

--Adrian

Edited March 16 by peril

[silverton]

Any fluid equivalent to Subaru ATF-HP is what you should use.  The capacity of the transmission is 10.4 quarts.  if you just pull the drain plug you'll only get about 4 quarts out. So if you do 3-4 of those you'll have mostly fresh fluid.  If you decide to do a flush by pulling the lines off the radiator have a friend help you determine which hoses are in/out.  Put the in hose in a bucket of fresh fluid and wait for the out hose to run the same color as the new fluid.  only idle while you do this, it takes less than 5 minutes. Near the end of this process it is a good idea to shift it through the gears (R, D, 2, 1 if applicable) so fresh fluid makes it through all the valve body channels.

[Scubaboo]

I did my drain and fills with Redline D4, which is the closest they have to Subaru HP from what I've seen.  I did 2 drain and fills. 

No problems so far, its been some years already I think. I hope I dont jinx it by posting that lol!

[SchwarzeEwigkt]

I did my last drain/refill cycle like four years and about 25k ago now. I have a Bavarian Autosport (RIP!) vacuum fluid extractor that I used to drain out as much fluid as I could via the dipstick. I seem to recall getting out something like 6L. I put the same amount of fluid — Idemitsu ATF HP, the OE stuff — back in, spot checked that it wasn't horrifically off, started the car and let it idle for a few, checked the level again, shifted through all the gear positions a few times, let it idle until it was warm, checked the level again, adjusted it, then drove about 10mi, checked it, and adjusted again.

At the time — being in the Before Times, when some of us still drove to the office rather than firing up the ol' VPN — I was putting on about 300mi/wk. I think I waited two weeks and then repeated my drain and refill process. I think calculated that I got like 80% of the fluid that way.

My observation was that the car immediately and still does shift more smoothly than it did with the fluid it had in it (may have been original at 90k, no records of it being changed and the PO had no memory of having done it), and it much less frequently bangs into 1st when braking to a stop. That is, it did it often enough before that I was mildly concerned and now it's done it maybe three times that I've noticed in the last five years, and each time much less violently than before. Think "thump" rather than "bang." I think I've got a sticky solenoid that's now much less so.

It went well for me and definitely justified my $70 spent on that vacuum extractor, though I've used it for a ton of other things since then. If you've got space to store one, I'd suggest u git u one.