I currently have a 03 TS with the auto tranny. The car currently has almost 60,000km on it and is 3 years old. The car is just a daily driver and is never tracked or raced.

Searcing the fourm, a lot of people say that they will bring the car into a tranny shop and replace all the fluid with using some sort of $$ synthetic, but most of those owners are driving WRX's and hence need the extra protection of synthetic. In my case I belive that I only need to replace it with OEM fluid (dino oil).

Having said that, do I still need to bring the car into the tranny shop to have all the fluid replaced? Is there any real benifit to doing a full fluid change vs. a drain and fill at home (I know I can't get all the fluid out with a drain and fill, but nothing is stopping me from doing it say once a year, or maybe even twice a year).

One thing to note, we tend to keep cars a long time in the family (12+ years) and thus long term reliability is important. Our corolla had it's tranny oil changed once a year (drain and fill) and when we sold it at 13 years, the tranny was "starting" to show signs of slippage. I'm not sure if that was because the tranny fluid was never REALLY changed or was it just because of age.

What i'm concerned that there are some areas (ie. torque converter) that unless you do a full flush, you will never be able to change the oil out... 12 year old oil sucks.

I'm not sure of the amount, but there is a portion of the fluid that remains in the torque convertor. Maybe 20% ??

Having said that, the owner's manual only recommends a drain and fill (not a flush).

-Dennis

A flush is for saps and is a marketing tool for shops that buy them. Your tranny is DESIGNED to be drained and filled, NOT flushed of 100% of it's contents. If it makes you sleep better at night, go for it, but it will add .000034444% better protection than a drain and fill for a ton more money.

Subaru recommends a drain and refill. If you take the plug out, leave it drain. Replace the plug with a new crush washer (same as oil drain plug). Add 3 1/2-4 qts of oil and check. Add from there. Subaru doesn't recommend replacing the filters at all. Not even the one outside the tranny.

I've seen the inside of 4 subaru trannies. If you look in all the nooks and crannies you'll find varying amounts of the same grey paisty stuff that sticks to the plug when you pull it. Is it going to harm anything? I dunno. Is it good to leave in? Again, I dunno. Will flushing it remove all that stuff? Who knows.

I think if you wanted to you could drain your fluid. Refill with some cheap stuff. drive around till it warms up. Then change it again with the stuff you want.

I really would'nt pay someone else to flush it though.


OOOPS! Again I'm an idiot. I missed the auto tranny part in his first sentence.

If you are really losing some sleep over this you can do what I did for the first AT change at ~ 20,000 miles. Do a plug drain and fill 3X times while driving 50-100 miles between each drain. The AT sump holds about 9.8 quarts and I am able to drain 4.1 quarts per drain. 3X times will give you about 92% all new fluid. Use a new crush washer on the last fill. After that I just do a drain and fill every 30,000 miles or so. I don't believe in machine flushes nor does Subaru appearently. Seems to be lots of problems shortly after a machine flush for whatever reason. JMHO Ed

ATF is cheap enough that drain/fill's basically cost me next to nothing, doing it more often (like every 6 months) is defently not a problem.

My initial concern was that the tranny NEEDS a full flush because there could be some part in the tranny where a drain/fill will never be able to get to. If all the fluid can be diluted out eventually then all is well :)

A flush is not a flush like a garden hose on a part. A "flush" is only exchanging the fluid through the normal oil channels and whatever the gear mecanisms sling normally. I see no real advantage to this. All they do is disconnect the AT cooling lines and pump in one and it flows out the other which you can do if your so inclined. JMO

i am a subaru technician and i recommend a flush it is amazing how little a drain and fill does. trust me- if you bring it in for a flush ask to see the fluid when they hook up the flush machine, it will be black and nasty and then ask to see what it looks like just before they disconnect the machine it is a world of difference the flush changes all of the fluid out if you plan on keepeing the car it is good to do about every 20k-30k miles

yes, ATF coming out (particularly during a flush) will be cruddy, but i've yet to see numbers that convince me that this translates to meaningful transmission wear, and it isn't too hard to find somebody who developed leaks after a flush. so.. one more vote for drain and fill...3x if yr nervous(yeah i did the numbers, too). incidentally, i've been suprised by 50%+ drains in the past, and had to keep going back to the store for more fluid. also, why skimp on the oil just because you don't beat your car?

this is all theory, of course. ask me again in a decade.

Update, I did a drain/fill about a week ago and the tranny fluid that came out was nasty... almost a "rusty orange" when it was comming out of the car (air bubbles?). The fluid did NOT have a burned smell to it but was not very transparent at all... way different colour than the stuff that went back in.

This week I did my second drain fill (after 500km of driving) and the fuild that came out of the tranny is much better, a "tad" darker in colour than the stuff I put in but looks to be in very good shape (you can see through the fluid when it's draining, and it's comming out red). I'm getting about 3.5L of fluid out of the system per drain.

The car is defently smoother. The tranny seems to shift smoother and the lag is shorter (when you hit the gas initially). I also changed the front diff, rear diff and engine oil at the same time tho.. lol..

In the end, i'll prob change the tranny fluid once more when I do the next oil change (5000km) then stick to a twice a year schedual :). Now that I know all the tranny fulid passages are connected, and that all the old fluid can eventually be diluted and drained out of the system I don't have to worry about flushes :).