Transmission

[Suprawill1]

Hey All,
Are there any cons to replacing tranny fluid with synthetic? Just a thought for added protection.

Also, is synthetic engine oil standard in these ST's? Don't know the last time it's been changed 'cause I just bought it but going to put either Royal Purple or Mobil 1 in.

Thanks!

 

[ChasBG]

Pretty sure the recommended trans fluid is likely synthetic. I would not put anything in my transmission except the Ford recommended fluid. PERIOD. Fluid is going to influence performance and wear in a very sophisticated transmission. I'm sure there are alternatives that list the same specifications but I just would not risk it personally and at a minimum I would investigate how it might effect warranty. And, I don't think changing to a different fluid is going to provide added protection. This isn't something you can do in your driveway with typical mechanical tools either. The transmission fluid has to be flushed out and replaced. I just don't think it's worth it. Get it flushed and replaced per the recommended intervals.

The recommended oil is a synthetic blend so a full synthetic would be a higher quality oil. I put Mobil 1 in mine on the last oil change. Lots (maybe most?) of owners use full synthetic oil.

 

[Cruising68]

Motorcraft ULV for the trans here. These days, not worth going off spec on trans fluid. So many variations now. I’d run Amsoil in the trans if it was the same at the ULV but many are too high in viscosity.


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[Suprawill1]

Thanks for the hits! I'll leave the tranny with Ford spec fluid.

Next engine oil change will be Royal Purple if I can still find it. Otherwise, Mobil 1 or Amsoil.

 

[Toe ball]

Thanks for the hits! I'll leave the tranny with Ford spec fluid.

Next engine oil change will be Royal Purple if I can still find it. Otherwise, Mobil 1 or Amsoil.

I would only use motorcraft tyranny fluid, just to play it safe. I was using Motorcraft full synthetic previously. I got a good price on Mobil 1 at Costco the most recent time