Changing manual transmission oil
 

Always take all appropriate safety precautions when performing any maintenance or service on your car. Set the parking brake, chock the wheels, and always use supports besides the jack when working underneath the car. Wear eye protections and gloves when appropriate.

Preparation: I drove the car around for about 10 minutes making sure I'd shifted through all the gears to get the transmission warm. Then I let it cool for about 15 minutes. While it was cooling, I assembled the necessary tools for the job: jack, jack stands, transmission oil, 10mm hex wrench, shop towels, hand pump, work light, mechanic's creeper, oil drain pan. CAUTION: Be careful when working under the hot car as you can get burned by touching hot surfaces or if you have hot fluids splash onto you.

1. Jack up the car. The jack point for the front of the car is well under the center of the car back behind the engine splash shield. I placed jack stands on both sides to fully support the car safely while I was under it.
   
2. First, loosen (don't remove it yet) the transmission fill plug. In case there is a problem removing it, you haven't drained all the oil from the transmission and can still drive the car. Now place the drain pan underneath the drain plug and remove the transmission drain plug. The drain plug shown is on the bottom of the transmission housing at the rear. Let all the fluid drain from the transmission. I snapped the photo after I had already loosened it some, my transmission is NOT leaking. :)
   Attachment 170845
   
3. Clean and replace the transmission drain plug. Per the FSM, the washer is to be replaced each time you service the transmission (Nissan PN 11026-4N200). I did not have the right washers as you can see in the photo below (I bought the wrong ones after being assured by an Infiniti technician that the same ones for the engine oil drain plug were also for the transmission and rear differential. Idiot. :mad: As you can see, they are not) After inspecting the washers I'd removed, it is not a crush washer and doesn't look like it needs to be replaced. I reused the same ones. Infiniti says to replace it each time, but most DIYers and dealership technicians do not replace it. I'll see if my tranny leaks.
   Attachment 170846
   
4. Remove fill plug and refill transmission with oil. The FSM states to use "Genuine NISSAN Manual Transmission Fluid (MTF) HQ Multi 75W-85 or API GL-4, Viscosity SAE 75W-85 or 75W-90" I chose Amsoil synthetic 75W90 API GL-4 Manual Transmission & Transaxle Gear Lube. The FSM states to refill and check the level by sticking your finger in the hole to feel the level of fluid. This is assanine. Unless you have no bones in your hands and wrist and a finger that is the diameter of a 3 year old and 6 inches long, this isn't possible. Once you get close to the fill amount (3 qts), pump slowly. When the fluid starts to leak from the hole, it's full. Be sure to measure when the car is level. As my front end was jacked up pretty high, after it was full I lowered the car and let the excess drain out of the fill hole until it stopped. This drained about 6 oz or so from the amount it held when jacked up in front.
   Attachment 170847
   Fill Plug
   
   Attachment 170848
   Transmission oil and hand pump I purchased for $11.99 at O'Reilly Auto Parts.
   
   Attachment 170849
   Using the pump to refill the transmission. Capacity is 3 qts + 4 oz or 2.93 liters
   
5. Replace fill plug. Tighten fill and drain plugs to 25 ft/lbs. Be sure to clean off any drips or spills on your exterior transmission case with degreaser so you can tell if you are leaking when you check later.
   
6. Remove used oil (dispose of properly), tools, and set your car down off of the jack stands. Take it for a test drive. After your car has sat overnight, check the underneath for leaks around the drain and fill plugs. You are done! :driving:

awesome write up! Always meant to do this as well. now I see its so cake Ill be doing it very soon. I plan to use Redline Gear oil, its red and super thick, they call it shock absorbing gear oil.

It's almost as easy as changing engine oil. What viscosity is the Redline you are talking about?

stuff is expensive as hell! but Ive used this in dog box race trannies for a few passes and after a teardown the gears looked like new still..

http://www.carshopinc.com/images/RED58204.jpg

heres the description..

HEAVY SHOCK PROOF GEAR LUBE

A unique lubricant containing a suspension of solid microscopic particles as an extreme pressure agent--unique solid dispersion which cushions gear teeth to help prevent tooth breakage and allows the use of lower viscosities. Recommended for heavily-loaded racing differentials and transmissions, Off Road racing and problem gearboxes. The viscosity characteristics allow the lubricant to resist throwoff and provide a film thickness similar to a 75W250 grade, while providing the same low fluid friction as an SAE 75W90.

http://redlineoil.carshopinc.com/pro...id/45595/58204

what i like about it is that even during a lot of heat it retains its thickness and its rated 75w90 but its really like 75w250 ..stuff is thick as hell!

FWIW, Red Line recommends a 50-50 mix of their MTL (70W-80 GL4, part number 50204) and MT-90 (75W-90, part number 50304) manual trans oils for the Nissan/Infiniti manual transmissions and their 75W-90 GL5 gear oil (part number 57904) for the G37S rear end with viscous lsd.

I use

Motul 300 Gear in the Transmission

Motul 90PA LSD in the Diff.

I can't complain.

So around how many miles should i change the tranny oil in my 6mt?

I changed mine at 3000 miles to Motul 300. It was dirty due to initial break-in.

I'll change it again at 20K miles and then probably every 30K miles or more depending on the condition 20K .

It really depends on your driving style.

LSD every 20K should be fine imo.

Awesome DIY, Jeremy!

nice wright up. odd that a tech would hand you oil washers for the tran and rear. i switched to motul a while back and couldnt be happier. and to the poster about the RL heavy shock lube. stay the **** away from that in street cars. i used it in my S2000 which i did track duty with and the rear end destroyed it self. and i mean majorrrrrr grenade. and that was on a cusco RS full race spec 2 way lsd.

How is this done for the 5AT? Is it even necessary?

The 5AT has automatic transmission fluid that probably needs to be occasionally changed. I don't see any DIYs for it on this forum though, check google I suppose. Most cars have a reservoir and/or dipstick for adding it under the hood, and you'd drain it under the car somewhere closer to the front.

This is a DIY for how to change the oil in the 6MT ONLY. Yes, AT needs to be changed periodically. This isn't the place to find or discuss it. Someone with a AT can do a writeup for that separately.

Anyone know of a link to where they recommend this? I can't find that on their site. Although I've read some people saying they used that, others just used the straight MT90 which I assume corresponds to the Amsoil pictured above.

Nobody knows? Does anyone else here use redline for transmission or diff fluid?