Everywhere i call to get prices on changing my trans fluid they all do a flush where they pump in new while pumping out old but its expensive is it really better to do that and not change your filter?

 

I know many will swear by a flush. But you asked is it better. My feeling is that so long as you drain both the pan and the TC, you are getting most of the fluid out. When I did mine I got over 12 qts. The process isn't difficult and if you are careful it doesn't have to be messy. On the other hand, I don't understand how they can begin adding new fluid chasing the old and not have them mix when they hit the pan. Thus, mixing old and new and not removing all the old. Or do they suck all the old out before adding any new? I don't think so.

 

getting alot of views but no replys come on people i need more than one person so i can make a decision. Nothing against your opinion Tiger I appreciate it

 

I would rather drain the tranny and torque converter myself. If they flush the system, they might dislodge some of the real fine pieces of metal that normally reside in some passages, and help the tranny to work fine. If the metal is flushed, you might end up with oversize passages and a tranny that may operate differently.

 

The way I understand the idea, they break into the transmission fluid cooling lines and the machine receives fluid from the vehicle while it introduces new fluid from a reservoir. When the operator sees the incoming fluid change in appearance to that of new juice, the "flush" is complete. I've been told it takes approximately 16 quarts to do a 4R70W.

So, I don't see stray particles becoming a problem, and you get a complete change of fluid.

Now, if I can get an authoritative answer to which fluid I'm supposed to use in my '99.

 

my first trans oil change i did myself. changed filter and14.5 qts out of 16. i found the plastic plug so i know it was the first filter change. the filter was not very dirty so from now on i'll just get it flushed. the ford dealer wanted $99 for a flush and it cost me $75 to do it myself.
you should use mercon V. i also added an additive.

 

I just added a B&M cooler, Jerry Mod to valve body, etc. Anyway, it took just a hair over 14 Liters. Figure 1 liter for the big cooler. That's the 4R70W and 4.6L , yours may be different. Lets put it this way. There are 4-6 quarts in the torque converter alone, probably another quart or just over in the cooler and lines, another quart or two inside the valve body and shift accumulators and servos, the rest is in the pan. If you do it yourself you can't empty the valve body, even a power flush won't do it unless you engage every gear while flushing. Can't clean the magnet by flush. Can't wipe down the pan (lots of clutch residue) with a flush.

My money is on disconnecting the top radiator cooling line, hook another hose to it, pump out the old into a container (at idle). When it spurts air shut it off right away. Drain torque converter. Pull pan off. I just added a B&M tranny drain nut as well to make it easier next time. Cost me $240cdn with largest B&M racing cooler I could buy, valve body gaskets, drill bits, semi-synth Mercon V. Can't complain and I know it's done right. Shifts real nice and crisp.