Why isn't there a 2nd drain plug on the bottom of AT oil pan?
 

Hi All,

I've been trying to trying to figure out why didn't Subaru/Toyota add a 2nd drain plug at the very bottom of the automatic transmission oil pan so it's easier to replace ALL (or what's in the pan) the oil at once. I know there's a torque converter somewhere that hold more fuild but that's besides the point.

Having to drain/fill 3 times seems like a lot of waste as you are draining of the new oil on the 2nd and 3rd drain/fill.

I've searched high and low for this answer and my thinking is that it could only be the following.

1. Keeping costs lower
2. Subaru/Toyota thinks we are stupid and we might screw up the fluid change somehow.
3. Something might go wrong if the transmission fluid goes below the level of the overflow plug during the fluid change.

I was going to insert a thin tube through the refill plug or overflow hole and suck up as much of the old fluid as possible to get the most old stuff out. I'd thought I'd ask you guys before something goes wrong.

Vic

I'd bet on your 2nd point.


humfrz

4. The engineers that designed the car were not worried about the little bit of oil left in the pan during a change.

Considering the amount of old fluid that gets left in the converter and the rest of the transmission during a typical pan drain/filter change, the few ounces left behind are of no consequence.

Do you happen to have a part # for the drain and refill plug gaskets?

5) Stupid engineers think you would rather just dent the pan when you scrape bottom on your low car instead of ripping out the drain plug. :slap:

Same for AT as MT?

There is, in fact, a drain plug.

http://i264.photobucket.com/albums/i...pspay0jfuh.jpg

As for the drain and refill procedure, I hear you, it is onerous and wasteful. Just make sure that you cycle the fluid like the service manual says. That way, the fluid goes through the valve body and torque converter.

Yep. Also the diff.

That wee bit of grit left down there is beneficial for the lifetime (or at least until necessary replacement or rebuild) of the transmission.

Meh. Compared to all the grit stuck in other spots that would be a pittance. Just don't let the car sit for several hours before changing it and it should all be stirred up anyway. If it doesn't stir up and just sits there we are back to it being a none issue.