Stick with regular Mercon/Dexron III or go synthetic? If you've run syn. what type and how'd the trans do? I'm going to be swapping out both the trans. and t-case fluids. I would like to sweeten up the shifting. Pulling into second starting out or coming back down I have to ease'er in, All other gears are fine.
Also can I grease the throwout bearing? I used to run construction trucks and got used to lubin the throwout bearing.
1989 F250 XLT Lariat 4X4.
Thanks
Duane

 

Synthetic mercon III is fine and is the required oil for diesel applications.

 

All S5-42 Transmissions (exc. D.i.t.) Use Dexron Ii / Mercon Xt-2 Qdx Or Ddx.

 

Thanks guys much appreciated!