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Manual Transmission Fluid Change


 
Part of the joy of owning a Jeep is getting to work on it. So I'm starting a new series of write-ups for basic maintenence type stuff, that every Jeep owner can do.
 
Did you know your manual transmission fluid should be changed every 18,000 miles? You should also check the fluid for water containmenation after each wheeling trip.
 
Changing the fluid is pretty simple really. These are pictures of my AX15, the drain plug is on the passenger side, as shown. The nut takes a 15/16" socket to remove.
 
AX15 Oil Drain Plug

 
Be ready to move the drain pan when you remove the plug, the fluid can really come out pretty quickly at first.
 
AX15 Drain Plug Removed

 
Also notice the end of the drain plug has a magnet on it, and it will have some metal shavings on it, be sure to clean these off.
 
AX15 Drain Plug Magnet

 
After all the fluid has drained, put the drain plug back in, its not a lug nut, it doesn't have to be super tight, just snug it up. Time to fill it, and you have two choices. One is remove the fill plug, and get the bottle in the fill hole, or the second choice is to pull the shifter.
 
Now you have two choices for filling the transmission:
 
-Use the fill hole.
-Pull the shifter.
 

Fill Hole

The fill hole is on the driver side, about mid way up the transmission (on my AX15):
 
AX15 Fill Plug

 
Just fill the transmission up until fluid comes back out the hole, then put the plug back in. As with the drain plug, this doesn't need to be super tight, just snug.
 
For proper fluid type, refer to the FAQ: Fluid Capacities.
 
Now my AX15 calls for a 75w90 gear oil, in the past I used 80w90 as it is cheaper and easier to find. However I've started using a Synchromesh type fluid, and I will never go back to gear oil. My AX15 shifts 100 times smoother with Synchromesh, and it no longer grinds when I try and downshift, the Synchromesh is well worth the little extra money.
 
I was lucky enough to get my hands on some BG Products Synchro Shift II.
 
BG Products Synchro Shift II

 
Mostly what you will find in the stores is Penzoil's Snychromesh.
 
Penzoil Snychromesh

 
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Pulling the shifter

Rather than try and fight with hoses or getting bottles up there, I always opt to pull the shifter.
 
On YJs there is a jamb nut under the shift knob, as shown the picture below. On TJs, there is a nut underneath the shift pattern. However because of the center console on a TJ, its probably easier to use the fill hole.
 
Remove the Shifter

 
Once you have the shift knobs and shift boot remove, pull the rubber dust boot upwards, that is visible at the bottom of the shifter.
 
Pull the dust boot

 
Under this rubber boot is a metal quick release ring (pictured below), push down on it and turn it counter-clockwise to remove it. It will raise upwards when you have it unlocked. After it is unlocked, the shifter will just pull out.
 
Release the quick release

 
Here you can see the tabs the quick release locks onto.
 
Here is the quick release

 
For proper fluid type, refer to the FAQ: Fluid Capacities.
 
Now my AX15 calls for a 75w90 gear oil, in the past I used 80w90 as it is cheaper and easier to find. However I've started using a Synchromesh type fluid, and I will never go back to gear oil. My AX15 shifts 100 times smoother with Synchromesh, and it no longer grinds when I try and downshift, the Synchromesh is well worth the little extra money.
 
I was lucky enough to get my hands on some BG Products Synchro Shift II.
 
BG Products Synchro Shift II

 
Mostly what you will find in the stores is Penzoil's Snychromesh.
 
Penzoil Snychromesh

 
I just pour 3.5 quarts in the top of the shifter tower, if you are afraid of overfilling it, just remove the fill plug and leave the drain pan under there. If you are just using the fill plug, just simply fill it up till fluid comes back out the fill hole.
 
Once you have 3.5 quarts (or however much fluid your transmission holds) back in the transmission put the shifter back in. The lock ring push down and turns clockwise to lock back in.
 
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© Copyright 2006 - 2017 Mike Lee