High Mileage 2002 PreRunner diff oil - Trans

Hello
First post here, newly acquired Gen 1, 4cyl auto 2.7, with 274K miles. There are limited service records available but from what I can tell, engine oil was replaced regularly. The rear diff fluid is another story. No way to confirm that was ever done, dear god.

From what I understand about conventional vs synth oil its generally a one way street. That is once you make switch to synth, don't go back to conventional.

This said my questions are
1. At this late stage, assuming it was never done, is it advisable to go to synthetic?
- I don't think I would want to use conventional in the off chance it had been done with synth before.
2. Is there chance of doing more harm than good by changing the fluid regardless of type?
- Wouldn't want to open a can of worms that'll put me in a bad spot.

Same story with ATF, no record of it ever being changed.
Here I think I'll take advise I've heard from others which is, don't touch it else you'll be having issues you didn't have before.

Neither of these are giving me trouble at this point but personally feel maintenance is better late than never especially where the differential is concerned

Any advise or suggestion is appreciated.

thank you!

 

False. That misinformation has been going around for years.
You can switch back and forth. Nothing is going to happen.

Won't hurt anything. Pick the one you like best.

None.

Pull the dipstick, If it look super nasty and burnt. I'd do no more than a simple drain and fill.
If it look even half way good. Then a drain and fill likely wont hurt a thing.

Better now, than never.

 

1) Doesn't matter here. Gear oil is gear oil as long as it's thick it'll be fine. 80w-90, 90, 80w-140, doesn't matter.
2) I think you'll be ok doing a drain and fill. you might do a couple 500 miles apart until the fluid looks clean. Just make sure you use the correct Toyota ATF. Should be type 4 which is kinda hard to find or use Valvoline multi-purpose synthetic. I did mine for the first time at 287k with no issues.

 

thanks for the quick replies!
surely going to do the diff first as it is pretty easy.
Valvoline Conventional 80-90?

 

Below graphics straight from toyota

 

That’s what I’d use.

 

Old fluids are laden with abrasive waste products, which eats the seals and wallows shafts.

Differentials are a special concern......since the only way to get a replacement is out a salvage yard...

 

That is a lot of miles for a first time ATF change. The potential issue is that the ATF fluid may be so saturated with contaminants that removing them may cause the transmission to slip. The only way to tell for sure is to send a sample to a lab for analysis and follow their recommendation. The next best course of action is to replace the ATF filter and clean out the tranny pan, taking close notice of the amount and type of gunk on the magnets and bottom of the pan - but you would need to know what is normal in order to make an informed decision.

 

how best to 'flush' out all that old nasty waste?

 

Just do a drain and fill. No machine powered flushes, just a good ol' drain and fill. That's it. Not going to hurt it, everything will be fine. A drain and fill is NOT going to replace all of your transmission fluid with new. So no reason to stress. Want to do it right, do another drain and fill in 3-5k miles or whatever interval you want to use.

When I did the 4WD conversion, I took a 1999 4Runner A340F (which was drained at the salvage yard), dropped the pan and replaced the strainer (you don't need to do this at all, the one I pulled was clean) and buttoned it back up. Refilled using the steps below and its been running without issues.

This is the process for a drain and fill:

Steps 1-5. Once fluid level registers in the COOL range, stop adding and go drive. Get it up to operating temp. Once at op temp, keep the engine running and re-check level. Continue adding until it is within the two dipstick marks in the HOT range. Once in that range, check for leaks, done.




Or, you can leave it as is. The choice... is yours.

Transmission fluid change, drain and fill,

 

how about the gearbox(es) flushing out the waste from the 75w90

 

Any gear stuff, I'd change again 6 mo later...
and then maybe every 48mo after that.

Those squeeze bottles got me spoiled




Diff is not that easy to flush because it circulates in the axle.

Old diff fluid has metal floating in it....
.....the rear seals not gonna like that..

Rear seal job at a garage $1200 avg with parts...
....since most of you dont have a floor press.

 

The magnet drain plug will not sufficiently catch enough small metal particulates?

Rear seal job much less than clutch job lol

 

Yes, this was my fear also.
I took a look and smell of the fluid when I first looked at the truck, seemed "OK".
Will look into lab analysis.
Thanks!

 

I dont have a lot of faith in those magnets,

but I got em everywhere you can, I put 3 xtras in bottom tranny pan,
but still use the inline one too.

Fresh fluid is king tho.....



I really think just keeping old fluid is a poor choice....
these are electronic instead of hydraulic shifting, so shifts dont require valves and such.

Scotty would say 'leave it alone' @ 150K+, but he also says save the old fluid just in case...
which doesnt set well with me......if it slips you can use the fiction modifiers to get back to friction ville.....

Fresh conditioners and additives does all kinds of good protecting different parts in the trans.

 

Finally got around to changing the rear diff oil today. Was happy to see it wasn't in too bad shape, just a little bit of shavings on the drain bolt. Must have been changed relatively recently although the previous owner had no recollection of it.
I was surprised to see only 2 quarts drained out.
Filled with 3 qts of Valvoline Conventional 80-90.
Now to take a leap of faith and drain/fill the ATF.
Maybe next weekend...

 

hopefully those rear axle seals are not weeping gear oil out into the drums,
have you inspected behind those drums?

 

I had the rear brakes adjusted and parking brake fixed about a month ago by a mechanic I trust. I would hope he would have mentioned oil there.
Now that I think of it, the previous owner did mention having the rear seals replaced, that's likely when the diff fluid was changed.
Is this something I can inspect from behind the wheels or do the drums have to come off?

 

if the weep is BAD enough you might be able to see gear oil moisture behind the rear brake backing plate whatever it is called

 

I know the shaft is crusty and the plate has some cancer, this has been a rust belt truck (northeast) its whole life.
Anyway, these pics show driver and passenger side
No signs of oil there I can see.