Differential oil change

My local NAPA parts guy said do not use synthetic gear oil in my 19 TRD OR, because it didn't come with synthetic gear oil in it from the factory. (he said its not good to mix the 2) I no longer want to use the Toyota branded oils & was going to use Valvoline 75W 90 synthetic but I figured it would be better to ask on the 4R forums what is correct.

This is for both the front & rear differential, not the transfer case.

Thanks !

 

There is data online somewhere? that supports being able to use synthetic in place of mineral based oil. I don’t believe the NAPA guy was accurate.

I just did all my gear boxes with Valvoline 75-90 synthetic. The squeeze bags where life changing! Much easier and less messy than the traditional bottle with pump.

 

Thank You ! That is the exact diff oil that I was going to buy until the NAPA guy made his comment.

When you drained yours, did you flush it out or just let it drain, plug it, then re-fill ?

 

I let it drip for awhile that’s it. Maybe on the rear and front diff I put the drain plug in temporarily and squirted a little new fluid in and then let it drain in an effort to flush out any residue. I did mine early around 24k because I was doing the engine oil, so it wasn’t very dirty.

True story regarding my experience with NAPA auto parts; many many years ago, my 68 Cougar with a 302 needed a new water pump. I took the water pump into NAPA and the salesman handed me a new one. It was a totally different shape and design, obviously not the right pump. He wanted to argue with me saying that his computer said it was the correct water pump. Anyone with eyes could see that they were physically different. That was my final and last experience at NAPA auto parts. My buddy had a similar experience with them when we were replacing a thermostat in his Ford truck.

I’m not an oil expert so I would encourage you to do some reading online regarding replacing mineral based oil with synthetic.

 

I had another thought. Next time I change the engine oil, I may pull the front diff fill plug to check the level. I still had the lift and diff drop when I changed the diff fluids so the front diff angle was different. But considering that now the car has the factory rake the front diff angle may be the same?

 

So is it fair to say that the original diff oil from the factory is mineral & not synthetic ?

 

Any off the shelf oil of the correct viscosity will work.

 

No clue, but if I had to guess, I’d say non synthetic.

 

I bought the synthetic Valvoline 75W 90 for the diffs & Royal Purple Synchromax for the T-case. I like the collapsible bags that Valvoline uses. Pretty sure that I won't need a transfer pump at all because of the convenience with the bag.

 

Just drain it well and go with the synthetic. Think of this change over as "synthetic blend" Next change will be "full synthetic".

 

I seem to remember back when synthetic oil first started appearing with regularity. A few people reported oil leaks afterwards. This was on older vehicles and the reason given was that the oil was too "slippery" and in some cases, caused leaks.

Not sure I agree, but that's what "they" said back then. FYI, I don't think twice before filling anything with synthetic. Only exception would be changing oil at all on a high-mileage auto tranny.

 

How many bags total did you buy for the gear boxes?

 

my 2016 runner changed the 3K miles nov16 ...rear diff had gray color looked it up my dealership,,, the diff oils are Mobil 75-90wt synthetic to change it .. then 2021 the diff oil is very clean looks like new ...

I use the toyota transfer case oil .. $80. qt ..had electrical devices in the transfer case ...had a lot of high amounts lube components ,, no wear issues..I also looked up the oil spec's ...

 

good info

 

I don’t remember for sure but I think 7 quarts. I added up all the gearbox capacities from the owners manual and added 1 extra quart which I didn’t need.

 

Yep, 7, but 6 will do.

https://www.4runners.com/threads/gear-oil.25838/

 

Amsoil!

 

I did the rear differential this morning. I was a little concerned about water intrusion because I haven't relocated my breather. As it turns out, I had nothing to be worried about. The oil is barely even discolored after two seasons of abuse.

 

TOYOTA ,, THE BREATHER REAR DIFF had a rusted issue on the diff.....then the diff has a high pressure and the axle seals are worn .. on the forum they changed the breather to the gas cap area ....
my GM 2000 truck in the gas cap area and the vent used a plastic vent ..factory ..

 

Huh?????

 

There is TSB on replacing the rear breather at the time of gear oil replacement. Cheap part, easy job and good insurance in my opinion.

 

Do you have a link to TSB by chance?

Thank you.