Anyone using synthetic oils is transmission or rear differential...

What brand is the oil?
What weight is the rear gear oil?

I was thinking of switching my trans and rear diff oils to Royal purple..

 

No text

 

Search and ye shall receive...

I can't justify the added cost over Motorcraft 5W20 to a synthetic personally. The oil in the rear differential is synthetic from the factory, and should only have to be serviced if (obviously) the cover is removed for differential repairs or the rear axle has been submerged, like when launching or retrieving a boat.

 

khendrix...be cautious here. I haven't checked Royal Purple products lately, but the last time I did I don't recall that RP made a tranny fluid that meets the Ford spec for MERCON V. There is mucho difference between MERCON & MERCON V fluids.

Your rear diff already has a factory fill of syn oil.

 

Did not know the rear diff was synthetic from factory..... *rephrase* didnt not remember.. I heard that before.

I havent looked at any products for trans fluid yet. Just wanted to know if anyone had changed em out for a synthetic trans fluid yet.

 

once my truck is broke in a little more.... (1700 miles on truck, 350 miles on engine)... I will be switching everything over to Amsoil....engine oil, tranny fluid, rearend fluid.

 

Amsoil, www.amsoil.com, has syn tranny fluid that meets all Ford's Specs.