I bought some Valvoline Dex/Merc for my transfer case but I'd like to know would Red Line be good? My google searches didn't give me an answer.

Red Line MT-90 seams to be the best choice for the transmission. But for the transfer case??

 

Valvoline should be just fine for the tcase. It's much less finicky than the trans is. I would change it any time I forged deep water anyway, but if you are trying to never change the tcase fluid again, a high quality synthetic would be desirable. I run valvoline ATF+4 in mine, because it's a synthetic and cheap, and I still change it every 30k miles just for fun.

For a 5spd AX-15, MT-90 is the best fluid to use. Its pretty expensive, so if your trans fluid was original like mine (around 160k miles old), I would run some 5w30 synthetic through it for a hundred miles or so to clean everything up.

 

depend on what transmission u have. If it's the automatic aw4 then u need to use dexron/Mercon 3 fluid. The manual 5 speed transmission uses redline mt90. The t case is fine with using any automatic transmission fluid

 

I run Valvoline in the NP231's in my xj, zj and Dakota for years. No problems at all, I wouldn't bother with redline

 

another vote for the dex/merc. I've had the same 231 for 5 years now and I don't even bother changing fluid. this same tcase has outlasted 2 different jeeps and lots of abuse and water crossings.

 

^ Same here that's all I use ^

 

I used Dex/Merc in my transfer case.

 

The transfer case is just gears, a chain, and a lightweight pump. Any 20w oil is going to be fine as long as it clings. I added a bottle of Lubegard to my 242 the last time, because the paraffin helps things move around more, but really anything is fine if the thing is working right.

 

Thanks everybody!

 

Thanks! I have the 5spd. I might do that. Mine has 260k miles. It should have been changed but who knows.

 

Yeah, should have been changed and previous owner doesn't really go together

Best bet is grab some 5W30 when you are at the parts store so you have it on hand. If the fluid looks pretty clean, just return the motor oil. If it is black like mine was, just throw some 5w30 in there, drive it for a bit (like 30-100 miles or so), and change it with MT-90.

I used whatever oil was cheapest at WalMart at the time, must have been Castrol or something.

Just be gentle while shifting with the standard 5w30 in there as my synchros are beat and didn't like how "slippery" the standard motor oil was (I suspect). It actually ran really smooth with exception to my dying 3rd gear synchro.

 

Synthetic oil is really good for the transfer cases. They get seriously hot - that low range planetary gear set is ALWAYS spinning.

Dexron is what they came with, but they're also certified by NPG/NVG for pretty much every ATF out there... synthetic 5w30 also works well. (Rockland Standard Gear studied lubricant performance in NP231s and found an evaporation issue with conventional ATF, and was impressed at how the 5w30 did - but again any light synthetic lube is fine.)