Max fluid exchange in an auto transmission...

[Food Scientist]

Without dropping the pan. Was working on my diesel and had recently bought a Mityvac. Vacuumed out about 4 liters of fluid a few days ago. Today I go to drop the pan to clean, inspect, and change the filter. Started taking bolts out and it started leaking. Vacuumed out another 4-5 liters of oil that had accumulated in the bottom of the pan over 5 days or so.

So if you do a drain and refill, have a Mityvac, and can let the vehicle sit for close to a week, you might be able to double the amount of oil you exchanged without getting dirty or making a mess.

 

[Trav]

Just get one of these..

https://www.amazon.com/Lisle-17892-Transmission-Drain-Pan/dp/B0002SR6WA

Place it on this and let it rip.

https://www.amazon.com/Lisle-17942-Black-Plastic-4-5-Gallon/dp/B000JFHMVQ/ref=pd_sim_263_19?ie=UTF8&dpID=41Wzl2HwhBL&dpSrc=sims&preST=_AC_UL160_SR160%2C160_&psc=1&refRID=QDHCF0DHDV41C472J32B

 

[John_K]

How about if you drain it with the drain plug and let it sit, would more fluid trickle out over time?

 

[Food Scientist]

This transmission in particular doesn't have a drain plug.

 

[AcuraTL]

If it's a Ford diesel truck, why not pull the pan (use the vacuum first or whatever), then pull the converter drain plug? That's 98% of the total fluid. If the pan level rises over time while the truck sits without starting it, the converter is draining back into the pan. Not the end of the world but fluid is escaping past a check valve and technically it's not supposed to. You will get almost half the capacity of the converter over time.

If they no longer use a drain plug on the converter you can use the cooler line method to ensure 99% new oil and it only takes minutes.

 

[Food Scientist]

You could pull the pan, drain the converter and flush the lines, but that involves a lot more work and 2 people to flush the lines. There is nothing wrong with that but I wrote this post for the people that tend to drain and refill and not flush the fluid. Also unless you have a lift at your house doing a flush would involve getting laying on your back, getting dirty and with the Mityvac you stay on your feet the entire time.

 

[HTSS_TR]

Originally Posted By: SVTCobra
Without dropping the pan. Was working on my diesel and had recently bought a Mityvac. Vacuumed out about 4 liters of fluid a few days ago. Today I go to drop the pan to clean, inspect, and change the filter. Started taking bolts out and it started leaking. Vacuumed out another 4-5 liters of oil that had accumulated in the bottom of the pan over 5 days or so.

So if you do a drain and refill, have a Mityvac, and can let the vehicle sit for close to a week, you might be able to double the amount of oil you exchanged without getting dirty or making a mess.

This is the main problem.

Not many have spare vehicle(s) to use while 1 is sitting for a week to drain the ATF.

I used Mityvac 7201 to do oil changes, ATF and brake bleed for more than 10 years. Mityvac and other fluid extractors are expensive, but for 1 time cost of $65(I bought mine 14-15 years ago) I had been using it more than 30-40 times so I got my money back already.