Two basic questions...flat 6 related
 

...albeit not Porsche related. I just purchased a 2002 Subaru with their 3.0 flat six. As with most of my car purchases I want to change the fluids. I've already done the oil and the front diff. Rear diff and auto trans are tonight. And I'd like to change the coolant as well. And I have to be honest that I have not done very much of anything on auto transmissions or with water cooled cars. This is our first automatic in 7 years and the old one everything was covered by the dealer. But I'm curious because I need to do a coolant flush on my wife's Mazda as well.

And before I get flamed I thought about posting on the Subaru board but it is sloooooow to get responses. I figured since it is basic auto and water info some of you guys, well at least the 944 guys would have some insight. ;)

My first round of questions involve the automatic trans fluid. Everything I've seen and read on the Subaru forums recommends these steps:
-Drain old fluid
-Replace with new fluid
-Drive the car around (time varies, but long enough to move the new fluid into the torque converter)
-Drain fluid
-Replace with new

The thought is that this is the best way to get the most fluid swapped into not only the transmission but the torque converter. It makes since but aren't you also just swapping dirty fluid for new fluid, and then barely used fluid for new fluid? Is this the best way (besides going and having a flush done at a shop)?

My second question involves coolant. The recommended process is:
-drain old coolant from radiator and tank
-fill with cleaner and water and warm up car
-drain cleaner and water
-fill with water and warm up car
-continue changes until water is clear
-then fill with new coolant

Maybe it is just me but putting tap or distilled water in the motor and running it until warm seems odd. At least this one as I understand you get all the old coolant out and then use water to flush. Then refill with new coolant. But is this the best way to go about a flush?

Sorry if these are super basic, but they both just seem a little odd to me.

Thanks

If you have a transmission cooler, it possible to break the connection to the cooler and provide a fresh fluid supply, and a container to collect the old. I've seen DIY write up's for Ford trucks, looks like it could be a big mess and just a pain to do it. I've always just swapped fluid. See if you can find out how much fluid comes out with draining the torque converter, then compare to the total system capacity. Then you know at least what percentage of fluid you are replacing each time. Long ago torque converters had drain plugs, guess it saved a few pennies, so those drain plugs long gone.

You can obsess over this if you are so inclined.

A simple drain and fill is what most do. You'll never get everything out, especially an auto trans (unless you have a flush machine), so dont try. Use good fluid and replace more frequently if you dont mind a little work every year or so.

Lately I've been using a vacuum tank to swap fluid. Yes, I know I am not cleaning the torque converter. It's easy and clean though.

I’ve not see an auto that didn’t have a cooler! Even if only part of the radiator. I've done this and it works well. But you must have everything you need including a big tub or you will fail spectacular (take pics ;)) I also try and change the filter. Not really much of a "filter" in most, but it helps to find pieces of clutch and other debris early.