Change now or later?

[bruce2]

I have got two cases of RedLine ATF siting there. The '91Q45 has 56+k miles on it and running fine. I have recently installed a B&M SuperCooler and Magnefine filter. I have been driving it literally recreationally since I got it. The transmission fluid in there, I believe it is the 20 yrs old original fluid, is clear as water; no color or burned smell at all. So, the question is, should I go ahead and do the 4 drain and refill routine now?

[Towncivilian]

Strange that it's clear and colorless. Since you've got a Magnefine installed, most if not all of the break-in wear and crud left over from the manufacturing process should have been filtered out by now. Since it's colorless and so old, I'd be inclined to change it. The fluid might have sheared down to an undesirably thin viscosity at operating temperature. Performing four drain and fills is rather wasteful; you can do a complete fluid exchange using the transmission cooler return line. Follow these steps:

You will need:

• 12 to 15 quarts of automatic transmission fluid
• A clear gallon jug, something like an empty milk jug
• Another large container to store used fluid for disposal

1. Disconnect the transmission cooler return line and secure it in a collection bucket such as a clear gallon milk jug. Disconnect the end leading towards the transmission.
2. Have a helper start the car while you watch the bucket - once it's half full (2 quarts), yell for the helper to stop the engine.
3. Add 2 quarts of ATF through the transmission dipstick.
4. Drain collection jug into larger jug (i.e. a Disposoil - these only hold 10 quarts though in my experience, so have something else to hold the last 5 quarts).
5. Repeat steps 2-4 until you're out of ATF.
6. Check fluid for proper level, and recycle the old ATF. Any place that takes used oil will likely recycle ATF.

[Skibane]

Yep. 20-year-old fluid that is water-clear isn't anything like fresh fluid.