05-22-2018, 01:04 PM
I have same engine and trans but had the clatter at idle so I drained and filled with 15-40 which got rid of all the clatter but I believe might have slowed my top end speed by several mph. Replacing with 15-40 is common with the ski boat crowd but only certain transmissions and I have not seen where zf has approved a zf63a for the switch assuming that is what you have. I plan on trying 5w20 next as that's about as close to atf as engine oil gets.


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