Using Trans Tune to help a contaminated marine transmission [SOLVED]

After buying a used marine transmission I found heavy buildup and water in the fluid. I drained all of the fluid and buildup that I can. Now I plan to refill with new transmission fluid and Trans Tune. What ratio of your product do you recommend using with the transmission fluid? The transmission is a 1986 model. The engine is a 12 horsepower two cylinder diesel. Top speed of the boat is about 5 mph. If you have any other suggestions I would like to hear them (for the engine as well).

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Jim D.
Jim D.
3 years ago

Sounds like a fun project John!  What I would do: Fill the transmission with the required amount of ATF, then add a whole can of Trans Tune. That’s all you need to do. Once you get everything running, check the new fluid to see whether it remains clear pink (healthy) or becomes milky (water emulsion). If milky, a 12 ounce container of isopropyl alcohol added the the fluid will help solubilize some of the remaining water. Running the engine/tranny will circulate the ATF and add heat to help evaporate the solubilized water as you go.

As far as other Sea Foam uses, I’d run Marine PRO in every tank of fuel to keep the fuel system and upper engine clean and protected. That should cover it!