Rear Diff. GS400
I let my friend borrow my camera, but the DIY change is even easier than a regular oil change. It's really easy. When you're under the car, take a look at the passenger side of the differential. There should be two star/hex bolt. I dont remember the exact combination, but there should be a lower and an upper bolt.
Tools Needed:
- (2) quarts of fluid, but you'll probably end up using 1.5 quarts
-Hex/star key. You'll need a somewhat big one so make sure yours fit before you start. I had to run out to my local autopart store to buy the key.
- Any type of pump where you can draw fluid and then inject the fluid. A siphon pump will not work (I tried, very messy result). Turkey Baster works perfectly fine!
- gloves
Basic Steps:
- Jack up the car
- Unbolt the lower bolt, which the differential fluid will drain down from
- Tighten the bolt back up
- Unbolt the upper bolt, which the differential fluid may be filled in.
- Take your pump and fill it up with differential fluid. Pump the fluid into the upper bolt.
- You'll know that you've put enough once the fluid starts to leak out of the upper bolt, and when it does, tighten the upper bolt.
- Lower the car
- Wash your hands
- Take a test drive
- Report back here
Warning: Gloves will come in handy. Differential fluid is probably the worse smelling fluid that goes into our car. Take a sniff and you'll know why .Having one of those orange hand cleaner will come in handy.
Tools Needed:
- (2) quarts of fluid, but you'll probably end up using 1.5 quarts
-Hex/star key. You'll need a somewhat big one so make sure yours fit before you start. I had to run out to my local autopart store to buy the key.
- Any type of pump where you can draw fluid and then inject the fluid. A siphon pump will not work (I tried, very messy result). Turkey Baster works perfectly fine!
- gloves
Basic Steps:
- Jack up the car
- Unbolt the lower bolt, which the differential fluid will drain down from
- Tighten the bolt back up
- Unbolt the upper bolt, which the differential fluid may be filled in.
- Take your pump and fill it up with differential fluid. Pump the fluid into the upper bolt.
- You'll know that you've put enough once the fluid starts to leak out of the upper bolt, and when it does, tighten the upper bolt.
- Lower the car
- Wash your hands
- Take a test drive
- Report back here
Warning: Gloves will come in handy. Differential fluid is probably the worse smelling fluid that goes into our car. Take a sniff and you'll know why
.Having one of those orange hand cleaner will come in handy.
Thread Starter
Joined: Nov 2004
Posts: 21,942
Likes: 64
From: FL
Thanks Henry.. Sounds pretty easy.. Is the hex key a 10mm allen wrench key by any chance.. ALso I'm i to use 75w90 redline fluid.. From what i've read on the search threads this is the fluid to use.. 
Could be another weekend project next week..
Tony
Could be another weekend project next week.. Tony
Thats the differential fluid I have in my car 
I dont remember what size the keys are. I did this months ago and I bought a set of hex just because
. Just get under the car and see which key it is.
I dont remember what size the keys are. I did this months ago and I bought a set of hex just because
. Just get under the car and see which key it is.
Driver
Joined: Mar 2007
Posts: 114
Likes: 0
From: ohio
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changing the fluid is like changing the engine oil. You need it for optimal performance. Plus the fluid needs to be changed because nothing lasts forever. It's a maintenance thing.
I dont know about lucas, but I recommend redline or amsoil. They have proven track record and most people have good experience with them.
I dont know about lucas, but I recommend redline or amsoil. They have proven track record and most people have good experience with them.
i had to ride my bicycle (not a big deal, I'm an almost-avid biker) to the parts store as no one was home, it was a weekday, and all my other friends were at work or out of reach... learned my lesson that day...
Agree with everything written so far. It is a 10mm hex key. I had to use it with a strong ratchet and the stock car jack to slowly push the ratchet handle up as I couldn't get enough leverage to loosen the fill hole (lying on my back, reaching up). You'l end up using around 1.5 bottles.
1 - Drench the plugs with liquid wrench or your preference. Will make it easier.
2 - Open the fill plug first as mentioned above. If you just cannot get this loose, forget about draining for now.
3 - Do this on a level area to get the right amount of fluid in. Kinda difficult if the car is uneven do to a jack on one end of the car. I have a steep driveway so I parked my car on the edge giving me enough room to work under the diff.
1 - Drench the plugs with liquid wrench or your preference. Will make it easier.
2 - Open the fill plug first as mentioned above. If you just cannot get this loose, forget about draining for now.
3 - Do this on a level area to get the right amount of fluid in. Kinda difficult if the car is uneven do to a jack on one end of the car. I have a steep driveway so I parked my car on the edge giving me enough room to work under the diff.
CL Community Team
Joined: Feb 2007
Posts: 9,388
Likes: 621
From: IL
Diff fluid is one of the few easy DIYs I'm not anxious to re-do anytime soon. Did it recently in my BMW 323i (along with trans, clutch, brake, and power steering fluid). To reiterate what GSteg said, the smell is EPIC. New diff fluid (I used Redline 75w90) smells worse than any automotive fluid has a right to, and used is positively gut-wrenching. I can't stress this strongly enough. Buy a CHEAP fluid pump and wear clothes you don't care about. The fluid pump will be going in the garbage no matter what, and if you get any fluid on your clothes, they might as well too, because you'll never get the smell out.
It's a very easy process, but next time I'll be paying someone else to do it for me.
It's a very easy process, but next time I'll be paying someone else to do it for me.