Last Sunday morning I finally got to the long delayed flush of my transmission.

I've had the ATF for a couple years!

I made an adapter for the upper radiator fitting using a salvaged oil cooler fitting from the previous replaced radiator. The thread size is identical to the internal heat exchanger port. I cut off part of the outer end of the hex which had the female threads using a hack saw. I then drilled and tapped the ID for a 1/4" FPT. I used a 3/8" barbed fitting from Home Depot and a roll of 3/8" ID clear plastic tubing. (About 8 feet.) A spare fuel injector "O" ring between the adapter and in the radiator port provided for no leak using only moderate hand tightening. (When taking the top pipe out of the radiator be sure to back up the radiator's adapter when you loosen the tubing nut so it won't turn and stress the internal heat exchanger. I also temporarily took the clips off that hold the two pipes together.)

I had bought a nice transmission oil funnel but found it wouldn't reach the short filler pipe on the car. (I used my 1/2" ratchet extensions with a flex joint on the end to turn and pull the dip stick out.) A length of 3/8" OD soft copper tubing just fit into the end of it allowing it to reach into the fill pipe.

With the adapter in place I placed a plastic gallon jug where I could see it from the driver position and ran the clear plastic hose to it. I was smart enough to block the tubing into the top of the gallon jug using a chunk of old heater hose but when I started the engine and the old oil started to flow the jug fell over from the reaction. I quickly shut off and then put the jug in the carton the ATF came in to keep it from tipping over.

I ran the engine until I started to see air in the oil going through the plastic tubing. This put about 3 quarts of oil into the jug. I put 3 quarts of oil into the transmission and drained the jug into the empty quart ATF bottles. The old oil was almost ink black but had no smell and felt OK.

I repeated the run till bubbles and refill twice more. By this time the fluid coming out was almost the same as the fresh oil. I wish I had another quart or two to get the fluid real clear. I guess if I had done it sooner 9 quarts would have been more that enough but with it this dirty 12 would have been perfect.

Since I had built the adapter long ago, I did the whole procedure while my wife was in church. (About 2 hours including clean-up and a short test drive.)

There really is no excuse to have dirty old oil in the transmission. I should have done it long ago! Hope this detailed recount encourages others to tackle this relatively simple job.
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'96 965, 16' wheels, Michelin Pilot Sports, rear 18mm bar + Koni, 204HP cams, 126K. Put 200K on '85 745 TD.