Coolant/transmission fluid intermixing

Asked by May 18, 2016 at 03:20 PM about the 2003 Dodge Neon 4 Dr SXT Sedan

Question type: Maintenance & Repair

My friends '03 Dodge Neon has
coolant/trans fluid mix on her trans dipstick,
and  in radiator reservoir. I saw someone
ask another user of their dipstick was milky
looking. This dipstick AND upper radiator
hose is coated in pinkish, milky, and
definitely mixed fluids. She has run the car,
and apparently at 5000 rpm's or so, it will
start to move....I'm actually serious! Is there
any way to know if it's worth a new radiator
and full system cleanout, or is the
transmission shot, and she should scrap it?
It's not worth a replacement trans, but I
could justify suggesting a radiator, and
installing it for her.

2 Answers


Coolant could be causing the tranny slippage, I would bypass the cooler in the radiator completely by adding on a cooler, flush the trans and get all the bad fluid out, add a can TransX and fill to specs and then drive it and see how it does, you may have to drain and refill it again. If you do then after the drain add a bottle of lubeguard and fill to specs, if it is going to work that should do it. Just cap off the connectors on the radiator where the trans cooler lines were connected, this will keep the coolant from leaking temporally until it is decided if replacing the radiator is needed. But even if the radiator is replaced do not reconnect the cooler lines, let the auxiliary cooler handle the tranny heat. HTH


Engine coolant will ruin an automatic transmission. Get a new radiator or get a transmission cooler ASAP. Also the transmission fluid needs to be replaced very soon.

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