Guys,

I have looked through the maintenance manual and owners service log and the information is very subjective. Based on driving conditions, towing, etc.

Specifically I am talking about front/rear diff fluid, transmission fluid, transfer case fluid, and engine coolant.

I am at 45K and starting to think about refreshing these.

Dealer says:

1) front/rear diff at 90k
2) trans/transfer case at 100k
3) weren't sure on coolant

I know folks have a lot of different opinions on these items.

Does anyone have the official recommendations from Toyota for normal driving conditions?

I used to have my own weird nuances on when to do these, and did them all myself and used all kinds of expensive additives, potions, and formulas. The 4runner is the first truck I've had that came with full synthetic front to back from the factory and I bought new.

So I am going to follow Engineer1's advice and mantra by following Yota's recommendations and use OEM fluids. Just trying not to over think things...

Stu

Good question and I'm curious to hear what others have to say. I'm at 36k and plan on changing my front/rear differential and transfer case oil when I do my 40k oil change. The manual says every 15k for those items but only under certain driving conditions. So what do you do if you don't drive under those conditions? Would be nice if they made a more definitive recommendation.

My 2 cents and plan:
Lube fittings every 6 months regardless of mileage to prevent them from not accepting grease.

Engine oil 1 time annually or @ 5,000 miles (RV towing sometimes). First free change @3,000 miles (completed).

Thinking about adding an auxiliary trans filter for annual replacement.

May change tranny fluid based on how much towing @30,000.

Never heard of changing diff fluids unless they got wet (this is why I'm curious about your thread). Anybody know if the transfer case does any work in 2wd?

Coolant is long life. No plans for a change at this stage (1 year new) I will drive this vehicle less than 5k annually.

The 0W20 synthetic motor oil is on a 10k change interval so I am cool with that now...took me a while to come to terms with 10k change...but that's what Toyota recommends.

Yeah diff oil is subject to breakdown like other fluids so some sort or interval is recommended.

Stu

The manual says to inspect every 15k. I inspect by looking for leaks on my trans, TC, and diffs. I'm going to inspect the fluids in the diffs and TC at 30k and most likely replace at that time and then make an assessment of future intervals. I'm not spending the crazy prices for Toyota diff and TC oils and my dealer won't even stock it in bottles or sell from bulk.
Here's a great link to an FJ site with info and other links including how-to's.
Which differential fluid - Toyota FJ Cruiser Forum

Found this interesting:
The 5AT and the transfer case are separate. Unless you've used the 4WD a lot the front diff and transfer case fluids will come out looking almost new. You can wait on those without worry but I would change the rear diff fluid.

I just got back from the dealer after getting the headlights and driveshaft replaced under warranty. Dealer quoted me $150 to get both diffs and the t/c fluids changed. He assures me they use bulk Toyota synthetic gear oil. Those prices are hard to pass up. I might go that route.

I wanted to change my differentials and transfer case lube at 20k miles just to get any break in particles out of the system.

When I asked two different dealers about differential and transfer case lube. They both said they just use 75w90 for both the transfer case and diffs.

I had no problem believing that the 75w90 would be fine for the differentials, so I bought enough Amsoil Severe Gear for both the front and rear. However I was sceptical about the transfer case, so I did some research and finally found and ordered the correct product. It is Toyota Transfer Gear Oil LF 75W.
The part number is 08885-81080. I ordered it online.

However when I opened the fill plug the existing fluid seemed very clean in both the transfer case and the front diff, so I just left them alone.

I did change the rear diff lube, it was a little dirty and a few metal particles came out with the old lube.

After having owned a full time all wheel drive Jeep that required frequent diff and transfer case fluid changes, I am happy with this Toyota, I think since I don't use the 4x4 all that much the front diff and xfer case should go quite a while before needing service.

I spoke with dealer yesterday and got some clarification on the fluid change interval:

1.) Front/Rear diffs and Transfer Case at 60k
2.) Transmission and Coolant at 100k

I hate to have the dealer perform these as it is easy work. Plus I have always been adverse to getting any work done by dealers. However with my current living situation I don't have room (read: garage or driveway) to perform the work and life is pretty busy. Its nice to have the dealer perform these items while I have the truck in for the other routine maintenance.

If i can negotiate the same price quoted above including the Toyota fluids. This is the route I am following.

Thanks for all the input!

Stu

ALL FLUIDS GUIDE: Beginner Fluid Maintenance

Do you realize this is a 8 year old thread. You posted the same thing on multiple threads, guess you are trying to get your post count up

I'm just trying to help out as many people as I can, and I'm a bored lol. There's no need to assume the worst here. Besides, what benefit would I even gain from getting my "post count up"?

How often should I Change my Trans fluid?

None of these have yet been done. Obviously the maintenance guide says ‘never’ on the trans fluid (sealed unit etc), unless Special Operating Conditions (towing, car top carrier, heavy loading), then it’s every 60k miles. Differential and transfer case oil is also never unless special conditions, then it’s every 15k miles.

2015 Toyota Highlander AWD 3.5 V6 Maintenance ...

Call me skeptical but I doubt your dealer is using the actual genuine Toyota fluids. That stuff costs us mere mortals an arm and a leg and seems difficult to acquire. $150 for labor and using genuine Toyota fluids doesn't seem likely.

Things may have been different 8 years ago, when the post to which you are responding was written.