Fluid Change to Synthetic..?

[scott slade]

Okay I did the internet research, and now i would like your opinion.  It is time to change the oil in the diffs and transfer case. I am thinking of going synthetic...  is it really as easy as draining the old fluids, as much as possible.. and filling with the synthetic..??  I just don't see why a shop would want almost a hundred bucks a unit to do this when it can be done in a driveway...?  I know this is a simple question,  but is it really that easy...??    Might as well do the transmission at the same time...

[BlackYJ]

I switched to synthetic in my tranny and t-case a few years ago and it made a big difference in my tranny.  I don't do the diffs because I used to change them multiple times a year and it is not worth the money for the diffs.  I usually change the oil in my tranny and t-case only once a year

If you go through lots of mud of water, then I would stick to standard dino oil in the diffs

[w squared]

Like others will tell you, synthetic is not worth the money if you will end up changing it frequently. That said, if you want to go to synthetic, all you need is something to catch the old stuff, some new fluid, a casket scraper, a tube of rtv, a can of brake clean, a socket set, and some rags.

If you're switching to synthetic, I would pop the diff covers after draining, clen thoroughly with the brake clean, scrape the sealing surfaces, lay a bead of rtv, bolt up, and refill. Might as well keep that synthetic fluid as clean as possible unti you get water in there...

[morerpmfred]

If you are running a Detroit or a lunchbox or true trac those style of lockers do not lock up well with synthetics in the diffs.

[Jrama]

If you are running a Detroit or a lunchbox or true trac those style of lockers do not lock up well with synthetics in the diffs.

Very true i just switched to dino, now my aussie wIll lock up in the parking lot on tight turns

[scott slade]

Good points,  the majority of my off roading is dusty trails at our place in the Mojave... but a lot of highway miles....  I like the idea of pulling the diff covers and cleaning it out... an oil change shop would not do that and still charge you up the..@$$.   I'll start with the trans and transfer first.  Thanks