Best way to switch to synthetic ATF?

[rs2k]

What's the best way to switch to a synthetic ATF? What kind of synthetic ATF is recommended? I have a 1998 5.0 AWD 4 speed with 127,000 miles. Should I replace the tranny filter?

 

[FIND]

To switch to synthetic.

Drain old oil

If you are changing tranny fluid, might as well change the filter, even if you were using conventional for the change.

Once you have finished draining oil, replace the pan or plug

Open bottles full of synthetic oil

Tip bottles until they are at an angle that causes the oil to come out of the bottle... Try to aim for the fill hole... Just like when using the toilet... No one likes it when you go get it elsewhere.

Wait until bottles are empty and tranny is full.

Drive your vehicle as you normally would afterwards.

You may extend your drain interval after changing if you prefer.

 

[rs2k]

What about the fluid inside the TC? Would it be better to use the ATF return lines to drain the tranny? If I did it that way I couldn't replace the filter without wasting a lot of fluid though.

 

[FIND]

Wait what? You want to change the fluid but you don't want to waste too much of what is inside of the tranny?

I'm afraid I am confused by your question.

You don't have to worry about the fluid inside the torque converter. They can mix no problem. If you want to change it ALL out, you are going to have to flush your tranny.

 

[rs2k]

If I flush my tranny then I can't get to the filter unless I end up using twice as much tranny fluid to do the job. (Drop the filter THAN flush the tranny.) If I drop the pan and change the fluid that way I can't get to the fluid inside the TC. If having a little bit of non synthetic ATF mixed with synthetic ATF then my guess dropping the pan is the way to go... unless using an old filter with all new ATF is better.

 

[FIND]

You can buy canned tranny flush fluid at the parts store and tranny shops that attaches to your tranny cooler return line. But even with a flush, you will never get EVERYTHING out of your torque converter... Only way to empty that out is to take it out of the truck and drain it.

 

[koda2000]

The torque converter has a drain plug. There's around 8 qts of fluid in the converter and around 5 in the tranny pan. If you're gonna do it, drain both. i don't think there's an advantage to "flushing" unless it's really full of crap. As far as using a synthetic fluid, I believe Merc-V is what's reconmended for your transmission and that's Ford's synthetic transmission fluid. I think using any more expensive syn trans fluid is just a waste of money unless you're planning to do some severe towing of off roading with this truck.

 

[FIND]

Ah... forgot there is a plug on these converters. Thanks Koda

 

[rs2k]

What's the best and safest way to gain access to the plug?

 

[koda2000]

put the truck on ramps or saftey stands. pull the rubber plug out of the bottom center of the bell housing, rotate the engine by hand, using a socket on the harmonic balancer bolt, until the drain plug lines up with the hole, remove it and wait for all the fluid to drain out (it will take a while).