My 03 Ex has about 71K miles. Mostly highway. Wondering when to change differential oil and transfer case oil.

I was thinking of using royal purple. I remember reading about some additive you need for the differentials (conditioner?). What is that additive, and would I need to use if if I used RP?

Thanks for your help.

 

Unless the diff has been submerged in water, it should be ok... Trans fluid should be serviced every 30k miles according to the Maintenance Schedule book I have. (newer models may have different intervals)..

For the trans, IMO, it depends on what kind of 'abuse' it's been subjected to.. I tow a TT about 6-7 times a year, so after I had the entire system drained I've been dropping the pan every year since, or around 15,000 miles... I only tow a total of maybe 2500-3000 miles in that year, but my fluid is still red and clear and zero issues, even after 185,000 total miles on the rig!

Best thing to do is pull the stick and wipe it on a white paper towel and see what color it is.. Compare that to what a drop of brand new fluid looks like on the paper towel and you will know what condition your fluid is.

Good luck!

Mitch

 

You need a bottle of Friction Modifier p/n XL-3 ifyou have a limited slip diff. I believe RP has it in it already, but I'd add a bottle anyways for insurance. Not sure about the transfer case.

 

Front and rear diffs and the tranfer case should be done around every 100k miles, IMO. Unless you suspect water may have entered any of the three.

Unless you use 4 wheel drive on a regular basis, I'd suggest shifting into 4-low and 4-high at least once a month. Just for a short drive in a parking lot or off road. This will get the fluids moving in the t-case and front diff, keeping things lubricated.

Transmission service needs more frequent attention.

 

Yeah diffs and t case are good for 100k assuming water contamination is not an issue. Trans every 30k, sooner is towing frequently

 

RP already has friction modifier for LS diffs in it.

 

I was thinking that RP might give me a little lower friction in the diffs. I watched an on line video of a 4x4 mag do a dyno test on a nice lifted Dodge or Chevy - changed all fluids and replaced w/ rp all around. lowered tranny temp and picked up 10 hp. I realize that is a small gain. Probably within the range of error on a 250+ hp engine. Just thinking that at 70Kmiles it wouldn't be bad PM, and maybe if RP is a little slicker, it might help in the mpg /hp/torque dept's.

I should find that video..

 

Change all those fluids every 30k IMO. Dif fluid was toast in my front dif (left stock fluid in after purchase... changed all others to quality fluids) after only 50k... front dif fluid was as good as water ! Total chit IMO.

Change transfer case, transmission, and both difs at 30k.

Why not ? Whats it gunna hurt ? I don't mind doing any extra light/easy work. Its cake, and gives me ease of mind.

Like said early, if ya submerge any of those parts under water or in some good gooey mud, change the fluids. Again, might be overkill, but i'd rather change fluids vs. parts.

 

I would NEVER, EVER go 100k

The reason they give these outrageous fluid intervals is simply to lower their "operating costs" so they can advertise owning a f150 as cheap.

Mercedes suggest oil changes at 15k...

They then began having sludging issues and all kinds of problems.

Lowered to 10k... still had the same issue

now its down around 7,500 and this is with their suggested oil Mobil 1 full synthetic.

just

 

now I need to know the best way to change out the diff and transfer case fluids. I've seen pictures of poping the bolts on the diff covers and let the stuff drain out all over the place.

is there a tool for siphoning or pumping the old oil out and putting new in? Same with the transfer case?

One last last question - (I'm at work w/no access to my owners manual) - does the owner manual state the capacity of the diffs and the transfer case? Otherwise, where would I find that info?

 

The owner's manual should have capacities - if you can't find them, go to amsoil.com and look up your vehicle in the online product guide, capacities are definitely listed there.

If I'm not mistaken, the transfer case and the front diff both have drain plugs. The rear does not, the cover needs to come off and then resealed with the correct silicone sealer. You can use a suction gun in the fill plug, but I don't think you can get much out that way. You will need a suction gun anyway to fill everything back up. They are only about 10 bucks at auto parts stores.

 

Ya, the T-case has a drain and fill plug. You'll be fine there. Front dif does not.

Transmission needs a specific machine that pulls old oil out as it puts new in. You can do it yourself too, if ya want. You'll need a pump, some hoses, and some buckets. There are threads that go into detail on this already tho !

Dif drain: Just slowly unbolt it. Take a screw driver and slowly pry the bottom part (leavin the top bolt in... maybe the top two or so if ya like) Make sure ya got a big oil "catch" below. They sell em at any Kragens/Autozone/etc.

 

The drain and fill plugs use a 3/8 inch square drive. The same size as your ratchet. I tool the ball out of an extension and it fits all the way into the hole.
The front diff has a fill and drain plug. They are on the diff cover.
The rear diff doesn't have a drain. The fill plug is on the driver side of the front of the differential just above the gusset. You only need Friction modifier for a limited slip diff. I use Royal Purple and don't add the FM. It is included in the oil.
The t-case has the fill and drain plugs at the rear. If you have a t-case skid plate remove it to access the plugs. Four 10mm bolts. One side of the skid plate is slotted so you loosen them and remove the other two and slide the skid plate off.

Make sure that the fill plug will come off before you drain the oil.

Regards

Jean Marc Chartier

 

Words of wisdom...

Make sure before you drain your rear diff, that you loosen the fill plug first! Don't be a dumb *** like me and figure out after your drained that the plug is really a biatch to get out... unless you have some good air tools (impact wrench).

My 2 cents... :-)