[JimAllen]

Next time save some money and do it yourself.

Drop pan, change filter, clean magnet, (install drain plug or pan with drain plug to make the next time easier), refill trans with the amount of fluid needed to fill pan only (varies according to year and trans), find trans outlet cooler line at radiator, disconnect and run hose (or an extension you add) into bucket, have the remaining amount of oil needed to a full change plus a couple extra layed out and ready to pour into dipstick tube via funnel, have assistant start engine, pour fluid in at the approximate rate it's coming out into the bucket (approximately 1 gallon per minute on a 4R75W), continue until you've used all the fluid but one quart, shut off engine, reconnect cooler line, restart engine, check for leaks and top off trans as necessary. If the fluid has gone dark, it's easier because it will change color and tell you all the old has been flushed.

For normal maintenance, this is a perfectly adequate way to do it. There may be some advantage to a professional flushing machine on a high miles trans that has never had a fluid change, but the cooler line "home flush" does a great job when you drop the pan. I wouldn't do it without dropping the pan. If you've seen the magnet all covered in iron fuzz, you'll know why.

The primary reason to change the fluid is to remove wear metals. According to my sources, the Ford filter in the pan is a 100 micron unit. Most of the wear particles in the trans are between 5 and 80 microns in size, so they circulate freely. Most of the wear metals are iron and copper (iron from planetaries and copper from the clutches and converter clutch), and these two elements can cause the oil to oxidize more quickly.

I'd recommend adding an inline trans filter too, which will extend your service interval significantly. Ford offers a rebadged Magnefine in a kit with all the fittings you need to install it, plus instructions (the service manual has more exact instructions for the F-150). It's # XC3Z-7B155-CA. The Magnefine is a 35 micron filter with a magnet and flow director. Tests show that 51 percent of the wear metals in a trans are ferrous, and the Magnefine will get almost all of those with the magnet. It passed all of Ford's OEM qualifications and is used primarily with reman transmissions. When a trans fails it dumps lots of junk into the coolers. Plus, reman trans are never as clean as newly built (which aren't all the clean either), so all that junk goes right back in to kill the trans. The install tech is supposed to flush the cooler, but some are flat-raters don't and say they do, so the failure rate for remans was pretty high until Ford started putting the Magnefines on with a remain trans. It goes on the return line to catch all the junk before it goes back in via the lube circuit.

I changed the ATF in my '05 F-150 at 11K miles just to clear out the manufacturing contaminants as well as the break in stuff (the magnet had a lot on it). I then learned about the Magnefine and installed it at 15K. I did before and after particle analysis on the oil and in just 2200 miles the ISO Cleanliness Code (Google it) dropped from 15/14/12 to 13/12/9... a major drop in contaminants.

Racor also makes a kit with a spin-on 10 micron (absolute) filter and I installed one on my '86 F-250. It dropped the ISO Code from 16/15/13 to 15/14/12 in just 423 miles.



It usually takes about 5000 miles to drop the contaminant levels as low as they will go according to the efficiency of the filter