Differential and transmission fluid change DIY?

Went to the local dealer today to get a quote getting the differential fluid and transmission fluids changed on my 2019 crewmax 4x4. Guy at service desk quoted $550 for transmission and $250 each for front and real differential and transfer case. $1300 seems pretty steep in my opinion. Although I am not a car mechanic I do have a lot of technical experience working in the aerospace industry. Since it is just changing fluids and gaskets I am thinking of tackling this myself. Has anyone else done this themselves? Is it easy enough to do on you own?

 

It is easy. I’m not a mechanic. I just took my time and listened to some good music. You will be fine.

 

Yeah, it's probably simpler than changing your engine oil. Just make sure you use 75W-90 on the front and rear diffs, 75W on the xfer case, and get replacement crush washers!

1. Remove fill bolt
2. Remove drain bolt
3. Drain oil
4. Replace drain bolt
5. Fill with oil up to fill bolt level
6. Replace fill bolt

Probably $150-250 in total for the oil itself.

 

It's really not difficult. You could probably have the whole job in a couple of hours. Did mine a few months back, here's a picture of my son playing with the crush washers.

Link for the washers I used:

$6 12pcs Differential Transfer Case Crush Washer Gasket Kit Compatible with Toyota Lexus Scion 4Runner Land Cruiser Tundra Tacoma FJ Cruiser Highlander RAV4 Sienna 9043024003, 1215710010, 90430A0003

https://www.amazon.com/gp/product/B0C4T3K4B9?ie=UTF8

 

My recommendations:

Hit the dealer for the following:
6 quarts WS trans fluid. You’ll have spare…
Drain/fill plug washers for the front and rear diffs, as well as the trans.

Visit blauparts.com for all of the Ravenol gear oil you need. You’ll get 7 quarts of 75/85 for the differentials and 2 quarts of 75 for the transfer case. The bottles are really neat. They have a tube that extends and allows you to easily squirt the oil in the rear diff and the transfer case.

You’ll need basic tools, plus a good quality 10mm Allen socket. Get one for a 1/2” drive if you’re needing to buy anyway. It’s for the front diff fill plug, and it’ll be ridiculously tight. Careful removing it, as you may flip the truck over when you pull hard enough…. Do not put it back in that tight!!!

Filling the front sill can be done with a small hand operated fluid pump or with a big syringe. I use a 200ml Mighty-Vac syringe because I own it. Really easy and nice to use. Plus, I use it for power steering fluid replacement (evacuation).

For the trans, you’re supposed to simply drain and refill. Should take about 4 quarts. A few ways to do this… Some folks measure what came out (drain bucket with graduated markings on the side) and put that much back in. Fine, but you’re trusting that it was correct to begin with. The “correct” way is to intentionally overfill a bit and get the trans to a specific temp range before pulling the “Check” plug. Excess fluid will drain out and you plug it off when it’s just a trickle. To read the temp correctly, you need a scan tool or VCI thingie. I use my HP Tuner with their scanning software. Some people use a temp gun and read the trans pan. Aim for the low end of the appropriate temp range if you do this. It’s not super accurate, but better than nothing.

There’s supposedly another way to put the truck into a trans fluid replacement mode by rattling the shifter around for a while. I’ve seen it online, but never tried it.

Filling the trans can be done with a hand pump, drill powered pump, or with about 5’ of 5/8” OD vinyl hose fished down from the back of the engine bay and into the trans fill hole. Shove a small funnel in the top side or grab an adapter for auto parts store that screws onto the oil jugs. Think I bought mine at Wally World for about $5 and the hose from Home Depot for another $5. Easier than pumping…

The transfer case is silly easy. The drain and fill plugs are simple 3/4” NPT pipe plugs. Use a little thread sealant (pipe dope) or a couple wraps of Teflon tape (don’t wrap the first two threads to minimize risk of any getting in the case) before you reinstall the plugs. Hand tight plus a couple turns should be fine. They won’t feel very tight, but you do run the risk of breaking the case if you get too carried away. You’re only holding the oil in. It’s not under pressure!


Be patient. Take your time. The front diff plugs are frustrating, but that’s it. Everything else is super easy.

It’s still not cheap!
WS is about $15/quart
75wt oil is $20 per
75/85 oil is $23 per

That’s about $200 for the diffs and case, plus another $60 if you only buy 4 WS. With gaskets, that 10mm Allen socket, and other minor things, you’re a solid $300 into this in parts. Still a heluva lot better than you were quoted.

 

That’s for all the good input. I will definitely do this on my own over the holiday period when I have a few days off work. I appreciate all the good tips.

 

May as well buy a 12-quart oil pan, a Fumoto valve, filter housing wrench, screw-in oil fill funnel, and a filter housing drain tool so you can start changing your own engine oil!

I pick up OEM filters from the dealer for $6 per and order 0W-20 from Costco. Regular price is $20 per 5-qt jug, but it’s been on sale recently for $16 per. I buy a case at a time, which is 4 jugs. Comes to $40 for an oil change that I can do quicker than waiting in line at a Jiffy Lube. And I know it’s done right…