So I go to the dealer to get some J2 ATF and decide to get the transfer and diff lube. They sell me 6 liters of MTF 75W80 for both.

Later I check the user manual and it calls for this.
Transfer case: Hypoid gear oil API classification GL-5 SAE 90
Differential: Hypoid gear oil API classification GL-5 SAE 80

Anyone know if they gave me the correct fluid?
I've seen posts where people have used other brands of 75W90 for both.

BTW, I have a 2008 Outlander XLS V6.

 

I used mobile1 75w90 since 60k...now at 166k miles. I checked the fluid in the diff at 130k miles and still looks really good. I'd go with a good synthetic...or use that and feel good too.

 

Ending going with Lucus 75W90 Synthetic gear oil. It didn't cost much more than non-synthetic lube. Transfer case and rear diff use about 1/2 litre each and ended up needing just over 1 bottle for both. I did waste a bit of fluid so if you're careful you might be able to get away with just 1 bottle for both. But I would buy 2 just in case. Just a few tips for the DIY.
Required tools are a 24mm wrench, 17mm wrench, and 3/8 hex, and a suction pump pictured below . There is no room to get a 24mm socket on the rear diff fill plug. You could probably use a large adjustable wrench for that as well. Each of the fill and drain plugs have an aluminum washer on them which immediately fell into the drain pan upon removal. Lastly, I had some concerns on the best way to be able to fill the fluid with the car level. So I jacked the car up to drain the fluids first. Then lower the car to allow more fluid to drain. Then jack backup to reinstall the drain plug. There was enough room for me to get under the car with a creeper to fill both the transfer case and rear diff without the car jacked up. Two other things to note. Remove the fill plugs before draining the fluids. That way if can't get them out you won't be stuck without a car to drive. And ensure the hose on your pump fits into the fill hole. I have to use a smaller hose as the one that came with the pump was just a little too big to fit into the fill hole. Here are a pics of the drain and fill holes I found from other posts that were helpful.

 

I don't think gear oil is as important as transmission fluid. In a transmission you have various clutch packs which require a specific amount of friction to function properly. So viscosity and friction modifiers work in conjuction to give a certain amount of slip and grip without causing wear on the clutch pack. So ATF is very important to get the right stuff.

For transfer case though, it's just gears turning, they just need to be lubed to prevent the metal to metal contact from wearing the gears.

Rear diff has a wet clutch, but it's designed to slip and vary the PWM signal as needed. It also shuts off when it reaches a certain temperature. So it's not as critical as the transmission.

 

I totally agree that gear lube can go a lot longer than the recommended service interval. I think that the service interval is for this vehicle is relatively short because the fluid capacity is only 1/2 liter. Do you know if there is a wet clutch in the transfer case?

I noticed there is small plate on the bottom of the transfer case. Anyone know what this is for? Leads me to believe this may be used for some type of service.

 

The small plate is just a door for service.

There is no clutch in the center transfer case. The wet multiclutch pack is in the rear diff, so service intervals should be adhered to for the rear if you use your AWD system alot.

 

Thread revival...
I started to change the transfer case oil on my 2010 Outlander V6 but I can not get the fluid to fill back into the case. Each time I pump fluid into the fill hole it just spills back out. Also there was not a 17mm bolt for the fill hole but rather a 12mm. I've turned the prop shaft half a turn to see if maybe the fill hole was blocked but still no good. It appears the fill hole is very small to begin with. Any suggestions? I really don't want to tow it to the dealer for this.

 

In my opinion, the fill plug cannot be a small 12 mm bolt. I am guessing that you removed the wrong bolt, and it terminates inside. If you stick a small screwdriver into the hole, does it come to a dead-end? I think if you look around more, you will find the larger fill bolt.......and not near the top, but somewhere half way up the diff.
Post a picture for us.

 

I'm at work right now so can't. I've looked the diff up and down and there are no 17mm bolts. The bolt I removed does not pass completely through the transfer case like all of the other 12mm bolts. Is it possible to fill the fluid by removing the service plate on the transfer case?