In most setups, AT coolant oil is Bypass oil from the Shifter Body and have very little or no pressure.
If you look at AT oil flow in FSM etc goes out from S-body to "cooler" then simply dumps in the oil pan.
For hard lines can be anything even soft copper tube. Think is 5/16" but finding 5/16" tube is hard to get in many places. Anything softer then steel is easy to crush by road crap... Steel and some others won't bend w/ many hand benders and tight radius. Is why many "reviewers" say bender broke 1st time and other things.
The "rubber" sections must be made to take Hot Oil. Vacuum, Fuel, and many others "rubber" hose types will fail and often soon. Even if doesn't "leak" wrong rubber can "rot" inside and flake off then plug the "cooler" etc.
many fools install a aftermarket cooler wrong and doesn't cool or cools too much and oil doesn't work right or worse cook off and unit dies.
you really want OE setup w/ "cooler" in the radiator so in cool/cold weather the AT and oil gets warm enough.
Even more so on the highway and locking TC because oil can cool off and be under temp to work right even in warm weather. TC generates most heat made in there and highway driving keeps it locked for a long time...
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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)
The Ogre's Fiero Cave
