I need to drop the pan and change my transmission filter. I also want to swap out most of the fluid with Amsoil. At $10 a quart, I want to minimize the amount of new fluid I waste. So, what is the best way to get most of the fluid out and also drop the pan? Should I drop the pan, reload with Amsoil, then do another drain/fill? Or, drain/fill first, then drop pan? Any other way?

I know most do a series of 3 drain/fills but that becomes an expensive proposition using Amsoil.

 

How about a drain & fill with stock fluid, drive for a few days. If what is in there after that looks clean, pump out through the cooler line until it runs dry. Then drop the pan and drain the differential. Clean pan, put back together and put in the Amsoil. That would get most of the old fluid out. Only a little bit would be left in the return line and it would be pretty clean since you just did a drain and fill.

 

So there is no problem draining the lines dry? I guess I was thinking of it like a brake line where you don't want to introduce air into the system.

 

To be honest with you I'm not a big fan of running the pump dry. But lots of people do it with no issues. I have heard several mechanics say that it is fine as long as you kill the motor as soon as you see air. I just have not been inside transmissions enough to understand the lubrication needs. I'm a drain and fill guy. You could do a series of drain/fills with stock fluid until it's clean and then drain and refill with Amsoil.

 

Transmission system is not air tight, there is a dip stick that vent air in and out.
Drain and fill by definition will get 40% of the ATF in the RX out, if getting most old fluid out is your goal, it is not the method to fulfill it.

I would drain what is in the pan, drop the pan, take out the ATF filter. Fill up to the amount of what is drained and drive for 45K and do a drain and fill. Not a drop of Amsoil is wasted if you don't want to turn on the pump to squeeze more old ATF out of torque convertor and ATF cooler.

 

What I dont understand is,I always flushed my transmissions in the past with those flush machines.And always had good service their after (always changed the filter too) I guess these transmissions are just more susceptible to dirt than other transmissions.