My mechanic recomends changing the transfer case oil in a 1997 f 350 4x4 i am looking to buy, would this be a good time to change the transmission oil, maybe a synthetic in both? The trans. is a zf standard.

 

change both of those and the fluid in your axles in one shot.

 

thats what i did to my 71.. i figured since i was under there might as well do it and good thing i did i was amazed at the oil that came out of the t-case. it was Nasssty

 

'93 F-250 5.8L 105,000 miles. Just changed mine a week ago. The T case fluid from mine also looked worse than I like. Dark red, and blackish but no burn smell. It looked bad enough that I flushed the T case with some ATF until the flush came out looking like it went in, about 1/2qt was enough. I plan to change it again at the next engine oil change to make sure the crud is out. Did the front and rear diffs at the same time. Front was very low and dark, rear was very dark but both smelled like normal gear oil.

 

You also asked about synth fluid. My opinion - Trans and T case are very expensive. Comparied to those synth is cheap. However dino ATF has worked very well for years in these devices. If it was me, and I was changing all the trans fluid, not just the pan dump, I would put in synth ATF.

 

Thankyou for your input i will give it a try next week!