My mechanic told me not to use synthetic transmission fluid in my F150, 300 six with an E4OD transmission because he is of the opinion that it will damage it.

Does anyone know why I can't use synthetic in the transmission?

I would also like to change the differential oil and replace it with synthetic. Is there a way to drain the differential oil other than removing the rear cover?

Thanks,

Smittyd

 

I've been told this buy a couple of tranny builders, but not because it will damage it. But because it is a waste of money, unless your trans temps are higher than normal.

Not sure about the rear, if it's an 8.8, then I doubt it.

 

I don't have any good reason. I do have an E4od with 246,000 miles on it and all I use is the factory reccommended transmission fluid and Lucas transmission treatement everytime I have it flushed and change the filter. It averages about every 8 months or so. I have maintained it like that since new and have no problems, knock wood. The E4od is a good transmission when you have the '94 or later with all the mods to make it last. It is expensive to rebuild and I'm just not gonna go synthetic. Your tranny, your choice, I just wouldn't tempt fate.

 

Thanks for the good replies. From what I am hearing I will stay with the conventional fluid.

Thanks,

Smitty