I want to do a fluid exchange on my 07 F150, 5.4L. It has 90k miles. I've done it before on other cars using the return lines. However, I've read some posts about the transmission cooling circuit having a thermostat that may prevent this. I had intended to drian a couple quarts at a time through the return line, top off, continue, until I had cycled at least the capacity back through the transmission.

Anyone know firsthand if this vehicle uses a thermostat in the cooling circuit? I'd like to do this job myself if I can. Nearest reputable shop is over 2 hours away, and I prefer to do my own maintenance when possible. Thanks in advance!

 

You can do it just like you said. Just disconnect the return line at the side of the transmission. Make sure the transmission is warm. Fluid will flow through the thermostat and the oil cooler flushing your system. I did mine and flushed 4 quarts at a time. I flushed a total of 16 quarts through the system.

 

Which line is the return line? I.E. how do I find which one to disconnect?