ATF swap draining pan and differential

[FL-400S]

FWD car. Its got a drain bolt for both trans pan and differential. My question is, do I drain both at once, then dump full amount removed down dipstick, then start and check level? Or will that be too much in the pan and none in the diff? I think it takes about 8 qts total. Thanks!

 

[scott37300]

What kind of car?

 

[Steve S]

A service manual is always your best friend. A chilton type is good. A couple of years ago my best friend asked me to help with the timing belt and major service on his Ferrari and I asked if he had a service manual ,he did so I helped him and all was good This year he asked me to help him do the same on his 2002 Toyota p/u. I asked if had a service manual, he did so I helped him and all was good.

 

[FL-400S]

2003 toyota sienna A541E transmission

 

[bustednutz]

I'd just do a drain at the pan. Refill with amount that came out and drive it. Then in a few months drain it and refill it again.
I just have a fear of screwing something up. One thing at a time. Do a pan drain and refill. You will be good.

 

[wiswind]

I have a 2003 Sienna.
I drained both at the same time.
Put the plugs back in and refilled.
They share the same fluid, and you are refilling the differential when you fill the transmission.
By draining the differential in addition to the pan, you get more of the old fluid out.

Just to make sure that what I had read was correct.
I put the plug in the transmission pan, and slowly added fresh fluid to the transmission through the dipstick location, with the drain plug still out of the differential.....until I noticed fresh fluid coming out of the differential drain location.
Then I put the differential drain plug back in.
Again, this was just a test to see if I was really filling the differential through the transmission, and I was.

A drain and fill of the pan and differential will not take 8 quarts.
8 quarts is the capacity of the whole system, and you still have up to 1/2 of the fluid remaining in the torque converter, cooler, and lines.
I do not remember how much came out of the drains for the transmission pan and differential.....and I had dropped the pan also, which got me a little more fluid.....then I did a cooler line fluid exchange.

However, draining and refilling the pan and differential, say every 15K miles should be good maintenance for your transmission.