Trans Fluid Flush - What's the Best Way?

I bought a rebuilt A518 transmission from a Chrysler master tranmission tech and put it in my '92 B350 van 28,000 miles ago. Thus I’d say it is high time for a trans fluid flush. The question is, what is the best way to do it? Every body says they “have a machine that flushes out all the old trans fluid and puts in new”. But how can I be sure that the process that whoever uses is really going to properly flush out the whole system including the torque converter? Is the “BG Transmission Flush” procedure the way to go? Or is something else? I already know not to go to a quick-lube place, or a national chain.

Why not just drain and refill? What does the owner’s manual recommend?

All you really need to do is drop the pan, examine it real good for any debris, change the filter, clean out the pan, re-install it and refill using ATF+4. Let the engine run with the gear selector in “N” on a level surface. Once the engine has warmed up check the fluid level with the gear selector still in “N” Top off as needed. I wouldnt flush it unless the fluid is contaminated. Do this every 25-30k miles. Glad to see you doing it now at 28k


The problem with the flush machines is they don’t clean the filter, they don’t even see it.

I guess you’ve gotten advice from someone who told you that the only way to get all the fluid out is to use a flush machine, draining will only get about half of it. That is true, but if you do a drain and refill, with filter change every 30k or so, you don’t need to “get it all”. You will get enough each time so that the replacement fluid provides enough new additives to keep the transmission going for a lifetime.

Thanks for the input, guys. I’ll drop the pan, change the fileter, and refill per your advice. Thanks!