Full Synthetic Gear Oil change interval
 

Decided to post in this section.

This will be my 3rd time doing this service on my 2008 T4R SR5 4x4. Every time i do this service I’m showing minimal fluid wear on my front diff, transfer case, and especially rear diff. For those wondering I am using Valvoline full-synthetic 75w-90 because it is cost effective and I replaced my fluid every 30k.

I have been using my car for 100% normal drives and 0% for towing or off roading.

I have researched on the forums and had little to no luck.

My goal is to not be cheap and at the same time not waste money on changing gear oil too early.

For fully synthetic gear oils, what service mileage interval have you guys been comfortable with...35k? 40k? 45k?

And what gear oil did you use?

Please share your experience, thank you!

Do i really need to change my differential oil?

How often should i change my diff fluid

Rear Diff Fluid Chang Question

Synthetic Differential fluid ?

Which Synthetic Differential Fluid to Use?

What gear oil? V8 4th gen 4x4

Which gear oil in rear diff

I used Valvoline gear oil VAVOLINE 80w – 90 GEAR OIL (conventional) in my 2005 4runner. They had no synthetic where I am.

I did the first ever Drain of three quarts at about 145,000 miles and plan on doing another after another 70,000 miles.

The interval of 30,000 miles isn't necessary IMO, but won't hurt.

I do no towing and no high-speed driving, and over 50 mpg seldom

My diff fluid was ok but black.

Someone posted that differential fluid doesn't ever need service, but I don't know about
that.

I've read some posters go 275,000 miles and never changed the rear differential fluid.

LIKE THIS POST below..

"I've seen many axles live past 300,000 miles on the original lube, but the stuff smells worse than dead dinosaurs should. It's enough to make most guys gag."

He didn't say these differentials had failures.

Full syn gear oil. 100,000 it doesnt gel or gum up. Most of the wear happens on break-in. Best to do it at 5,000 miles then synthetic every 100,000 miles with a quality lube like Amsoil. Just keep the breather clear.

When I have drained lube after 30,000 miles in the past, it looked like new fluid coming out and it didnt stink like conventional lube does. Its actually cheaper in the long run to go syn

I use Castrol Gear Oil. My rig seems to like it.

Just checked my diff breather and its in good working condition, that was a good tip!

Thank you all, you guys are the best. All this info helped out a lot.

I have 3 4runners in family, changed to synthetic after first 25k in all 3 and change differential every 75-100k in all 3. None come off pavement. I think going 100k between changes is fine. All now approaching 300k, all good.

Unknown history on mine so I changed all driveline fluids when I got it at indicated 60,000 miles. Rear diff oil looked a little silvery/cloudy, but I have nothing against which I can compare. (Any pics to compare against welcome)

What I did was use a decent semi-synthetic as a flush for the first year.

I now have some of this ready to change in the summer.

Motorsport CRX 75w90 NT+ - Millers Oils

It's been interesting seeing how long I can leave the good stuff in for.

I run Amalie Elixir full synthetic gear oil. According to Amalie, it has up to 500,000 mile oil drain intervals capabilities. I once heard a mechanic say the 30k drain interval was overkill. I would agree that would be overkill provided no towing or wheeling. I’ll probably just inspect every 30k and only change if it looks dirty. I run this in my Tacoma that has 315k miles and I only charged once and have not had issues.

Bought my 4th gen at 100k with little to no known history so I changed both diffs & transfer case with valvoline synpower 75w-90 & a cooler hose flush of toyota ATF-SW in the transmission. Now here I am hitting 200K so I'm about to do a repeat. Just waiting now for the weather to break on a day off.

My 4Runner sees very little offroad use. So this interval is fine, BUT waaaay back when when I used to routinely dunk my 85 Toyota 4WD pickup's diffs (and everything up to the headlights on 33" & 3 1/2" lift) underwater I would change them MUCH more often, like after every serious mudding outing and at least once a year. Every time I could see where water had been entering the diffs through the breathers fouling up the fluid right good. Looked like mud and stunk way worse than gear oil already does. I managed to put almost 400k miles on that truck before I gave it up. No way would they have made it for all those years and dunkings like that without failure had I not kept the fluid changed so often.