Stock '00 XJ, 4x4 of course. Don't do any major wheeling (yet), just the fleeting dirt road and mud puddle expedition. It's my daily driver, sees about 10-15 miles of highway travel every day.

I'm not sure of the condition of my diff fluid, so I want to go ahead and change it to be safe. What's the best NON-SYNTHETIC fluid to use?

 

Your owner's manual should tell you - it's in the glove box.

There's probably no such thing as a 'best' dino lube since the cheapest synthetic is so much better. Some carmakers even rate their original synthetic lubes as lifetime cuz they last so long.

My '96 takes GL-5 75W-90 gear oil - I'll bet yours does too..

 

being the fact that the front axle isn't perfectly sealed unless you have aftermarket outer seals contamination can get in and even with offroading (considered an extreme driving condition in owners manual) they should be changed more often than normal anyways...so any 75w-90 would work or you can do 80w-90

 

The tow package, especially if you will potentially be towing something, asks for thicker oil (I think 85-140).

Whats with the synthetic hate? I wouldn't dare put it in my engine (I already leak like a sieve) but i think they ask specifically for synthetic in the diffs

I filled mine with royal purple 2 weeks ago, so now all my fluids are color-coded so I can tell whats leaking. Not a drop has fallen from my differentials since the change.

 

My take on synthetic is that regular old conventional oils have worked for years and years and years. You can go find an old chevy left to die in a field and probably get the thing to turn over and run.

I live by the "if it ain't broke, don't fix it" mantra, and i'm good about keeping up on vehicle maintenance, so using conventional oils is fine for me.

 

thats funny. If you check the bottles of your local stores "dino oil", on most of them you will find that its a synthetic blend.


Theres a reason why everyone is switching to synthetics. If we never "fixed what aint broke" we would still be riding horses instead of driving cars.

And to stay on topic:

Run whatever the factory recommends. Pretty sure its just regular 75w/90 or 80w90 gear oil.

 

While I totally agree with you in principal, synthetics have shown better fuel mileage results - in the block and the drivetrain - and are simply far better lubricants. Still, with a difference of over $70 between dino and synth in filling the drivetrain, I went a cheaper dino refill on my diffs and tranny this time and will suffer any performance consequences gracefully.