Anyone have a recommendation on pure synthetic or synthetic blend gear oil for my transfer case and difs. My local Oreily and auto zone only carry the synthetic blend. What are the advantages or disadvantages.

 

I recommend Royal Purple....I run it in everything, but then again, I sell it too. Mobile 1 makes a good oil that is a little cheaper.

 

No real diff between the two, full syn will last longer than the bled.
For a point of reference you will get about 30,000 out of dino gear lube, 40k with blend and 50k with full syn.
This all depends on your driving conditions and habits of course.

 

I asked myself the same question before doing my 60K service. From what I gathered on the forum if you do a lot of wading you probably want to change diff fluid more frequently and in that case you should consider dino or blend otherwise it gets expensive fast.
If you go with heavier oil (eg 75w140) Mobil 1 is actually more expensive than Royal Purple so watch out for that. Mobil 1 is much more widely available though. For full syn you can't go wrong with either.

 

You want and Need a full synthetic gear oil if you live in the cold. It is also great at keeping the temperatures down in the heat. If you lived in the cold I would suggest 75w90. If you leave down south and do some towing, or off-roading, or a lot of in town driving then go with 75w140.


I am 99% sure the 03 and 04 have breather tubes on the diffs so water does not get in. I have waded a lot and never had a problem.

 

Yup my '03 has breather tubes front and rear. Not knowing what Muddy has it was just a word of caution. I agree with Jupiter that if you don't change your diff fluid often full synthetic is what you want.

 

All Disco's have breather tubes.
I wade alot so I change my driveline fluids every spring and I use dino lube, 85w-140.

 

there is a difference between royal purple and mobil1,though not a huge but a little different.I say this because on my race car and in a couple friends race cars we always ran mobil1.when royal purple came out and made their hp claim,which was if you changed all of your fluids to royal purple you would gain around 15hp.We did it on my friends car and dynoed it before and after and he gained 12hp.which isnt huge when you started with 486 at the rear wheel before.But hey every hp counts.

With that being said i now run it in everything i own and love it.I never have any problems finding it.

 

Just remember all D2's came with a full synthetic from the factory and that is what is recommended. I prefer the 85/140 because of my lockers and high mileage.
Some will use dino gear oil but change it every year or less depending on how many water crossings they may do.