I'm thinking about placing synthetic fluid in the front and rear differentials. Any pointers or recommendations on fluid to use? I was going to use mobile one, but open to others. Do you have to drop the shield in the front to access the plugs to fill/drain? What about changing the transfer case fluid to synthetic at the same time? What weight there?

Thanks all and have a great night! I love this site! <img src="/forums/images/graemlins/kewl.gif" alt="" />

The people who've been around the longest here use either Amsoil or Royal Purple synthetic gear lube. Those are both 75w90. You can use 75w90 in both diffs and in the transfer case. It's been several years since I've had stock skidplates, but yes, I think you'll need to drop them first.

(Don't use Royal Purple motor oil in the engine, though, since they use completely different chemistry than other brands and it's definitely not intended for long interval use. Amsoil motor oil is the opposite and is intended for longer interval use than any other brands).

Years ago, I think one of the first 4Runners to get people to look at Amsoil was Gadget. I think he uses Amsoil motor oil and Royal Purple gear lube. His web site is www.gadgetonline.com

It's significantly easier to use a squirt bottle for both diffs and the transfer case. Amsoil doesn't come in a squirt bottle, but Royal Purple and Mobil 1 do come in squirt bottles. So get one of those first and save a bottle for future possibilities.

I've used Amsoil in everything and love it, except for their lack of squirt bottles for gear lube. If you go with Amsoil, know that it's best to sign up as a preferred customer and stock up on it for a while. It's much cheaper that way.

You might double check your owners manual, since I'm familiar with up to '02 4Runners. In previous generations, Toyota spec'ed 80w90 gear lube for both diffs and the transfer case. Everyone uses 75w90 for aftermarket stuff.

Thanks for the reply. Yes the 75W90 is just fine, though mobile 1 comes in 75w140 I think for the gear lube. I've heard that's okay too? Have you? I figured I'd have to drop the shield after looking over the weekend, oh well. I'll probably do all 3 at once. I don't have the LSD in the rear per my VIN #.

Thanks again. <img src="/forums/images/graemlins/kewl.gif" alt="" />

Kewlynx posted the link to the maintenance in another thread, Here's some info that might come in handy!

2005 4Runner (all 4 generations, as far as I know)
Capacities:
Front diff - 3 pints
Rear diff - 6.5 pints
Transfer case - 3 pints


pump from Amsoil, will screw right on the oil bottle.

https://www.amsoil.com/storefront/detail.aspx?ID=5814

Also try any local Marine Stores, and look for a "lower Unit" lube pump.
Some auto parts stores carry them as well

I thought I would post up the part numbers for the crushwashers, if you need to replace them. Hopefully this will help someone out in the future!

Front Diff Drain
9043024003

Rear Diff Drain
1215710010

Transfercase Drain
9043018008

Oil pan drain
9043012031

Always remove the fill plug first. That way if you cannot get the fill plug off, at least you have not drained the diff.

You will need a 24 mm socket for the rear diff and transfer case plugs, but a standard 15/16" socket may work in a pinch.

You need a 10 mm hex key for the front diff.

You may also need an additive for the Limited Slip Differential. Just thought I'd mention it! Mine doesn't have the Limited Slip!

Last, but not least, remove the FILLER plug FIRST, and the DRAIN plug LAST. Otherwise you might say bad words. <img src="/forums/images/graemlins/shame.gif" alt="" />

Thanks to you both!