I have a 91 YJ 4.0L manual with alot of miles I bought not to long ago. I would like to change the fluid in the trans and transfer case. I was told 80
90 for the trans, and I haven't checked on the transfer case yet. Someone else told me it might need automatic fluid or a different type of fluid for the trans so I haven't done anything yet. I don't have the manual of course. What should I do? Any web resource's out there?
Would Daimler Chrysler know? I have been told they only go back so many years?
DO NOT put 80w-90 in your transmission. It requires a GL3 or GL4 (low or no sulphur) gear oil, other wise the synchros will not be able to function properly and you'll get serious cold gear clash when shifting. DC has a special gear oil for AX15s, plus another for the later NV3550 used in the TJs. Check with your local dealer. Alternatively, you can use Redline MTL. I've used it in my '94 YJ for years and swear by it.
I find your description of my assitance to this guy offensive and uncharacteristic of you. What I stated is fact. The AX15 can not tolerate
80w-90 GL5 gear oil. DC recommends a special GL3 (no sulphur) oil available from Jeep dealers. They also make a special GL3 oil for the NV3550, which has the same issue re: GL5 oils.
If he uses any form of GL5 gear oil he will experience difficult to impossible shifting (esp. in extreme cold) and substantial gear clash. Sorry if my reply offended you, it's just the facts.
The original manuals called for a 75w-90 GL5 oil and were corrected by tech service bulletin years ago. Any 80w-90, even if a lower sulphur GL4, is far too heavy a lubricant for an AX15 or NV3550. I believe Redline MTL is a
It calls for a 75W-90 GL-3, and there were some years when the shop manuals incorrectly called for a 75W-90 GL-5. Redline's MT-90 is a 75W-90 GL-4, MTL is 70W-80 GL-4. If you go with Redline, MT-90 is the correct viscosity.
Thanks, Jerry. If he's in a cold climate he may want to consider the 70w-80 fort improved cold shifting. I put the original fill of Red Line MTL in my '94 YJs AX15 at 30k miles. I changed it last year as part of the 60k mainenance and noted the drain plug magnet didn't have a single flake of metal on it. Great stuff!
The owners manuals for the YJs and XJs through at least '96 also called for a 75w-90 GL5. I'm not sure when DC caught on and started using the GL3, but before that MTL was about the only thing available that would stop the synchros.
The 75w-90 GL3 sold by DC is quite pricey but works well. I put it in my '96 YJs AX15 three years ago and it immediately eliminated hard cold shifitng. When I looked this a few months ago the dealer came up with two different gear oil part 3's, one recommended for the AX15, another for the NV3550. They claim to have used the latter with success in the AX15, but if one is ordering this stuff might as well get the correct number.
Now you say it's 'ok' to use redline GL4, but don't do it because it's supposed to be GL3 which redline doesn't make, but use redline because it is better.
Oh and 'don't use 90 weight because it won't shift, but meanwhile 'you' use MTL which 'is' 90 weight which is 'great stuff'.
So just what the heck is it?
'I' know to use the GL4 'gear oil' for transmissions and to make sure it doesn't have the limited slip additive for differentials.
'I' could only find the GL4 diff fluid once when changing oil so used it. My shifter stopped working shortly after.
'I' then went and found tranny gear oil which only came in a semi synthetic at my local parts store, all the 'regular' gear oil had the limited slip or friction modifiers in, and now I have a sweet smooth shift.
I guess so, 'cuz we have no idea idf you're talking about me, Bransford or both of us.
supposed to be GL3 which redline doesn't make, but use redline because it is better. <
Nope, you're not paying attention. DC recommnds a GL3 75w-90 (which is a 75 weight oil, not 90w.) GL3 has no sulphur additive at all, GL4 is low sulphur. Redline makes 2 oils for manaul trans: 1) MTL, which is a 70w-80 GL4, and MT90, which is a 75w-90 GL4. MT90 would be closest to DC spec for an AX5 or 15.
use MTL which 'is' 90 weight which is 'great stuff'.<
Pay attention: MTL is a 70w-80, that is, a 70 weight oil. MT90 is a 75w-90, that is, a 75 weight oil.
How many more times do we have to spell it out?
doesn't have the limited slip additive for differentials.>
Now we're getting somewhere, partiularly in an AX5 or 15.
My shifter stopped working shortly after.>
Likely unrelated to the GL4.
synthetic at my local parts store, all the 'regular' gear oil had the limited slip or friction modifiers in, and now I have a sweet smooth shift.<
Jerry, a 75W-90 is a 90 weight lube at normal operating temperature. The
75W is its' weight when cold... and the 'W' means Winter. Same with 70W-80, it's an 80 weight when at its normal operating temperature and a 70 weight when cold. :)
The "cold" rating of an oil (i.e., "70w-x") is an oils actual petroleum viscosity, the other rating (i,e., "Xw-90") is its "petroleum equivalent" rating at average operating temp and is simply a rating based upon the effectiveness of its additives.
Thus, a 75w-90 is actually a thin 75 weight oil when cold, but becomes the "equivalent" of a 90 weight oil when hot. Same with multi-vis motor oil.
Most wear and shifting problems occur when a unit is cold. Thus, because of it's superior flowing capabilities, a lighter oil is best under that condition. However, under higher temps and load a higher viscosity (90w) is better. To get the best of both worlds petroleum engineers start with a light weight base stock, then introduce additives that increase its capabilities under heat and pressure.
The sulphur content of gear oils adds a complication: higher sulphur content (i.e., GL5) in a gear oil is an advantage when the oil is under pressure, such as when it's squeezed between a ring and pinion. Unfortunately, that very advantage becomes a disadvantage re: synchronizer rings, which must have enough friction capability to stop spinning gears to avoid gear clash. High sulphur content oils compromise that function. Thus, engineers specify lower sulphur (GL3 or CL4) oil in transmissions to keep cold synchros happy.
This stuff is really easy to see. Compare a bit of 75w-90 gear oil to straight 90w and it's easily apparent which is the lighter oil. You can also easily smell the difference between a GL5 and GL3 oil, the GL5 stuff stinks of rotten eggs to high heaven, the GL3 stuff smells more like motor oil.
Heh, one of the few things I regret doing in this life is changing the original transmission fluid in my YJ. Coincidence or not, shortly thereafter the second gear synchro went to hell. By the time I figured out what had happened the original oil had been picked up by the curbside recycling people. I got the transmission back to a semblance of normality by putting Mobil 1 synthetic (75W90? without the limited slip modifier) in it, but I still have to hit second at just the right rpm, or double clutch it, to prevent grinding when shifting into that gear.
The original poster should drain his transmission fluid into a clean container, strain it through a chamois, and pour it back in. ;o) Manual transmissions "never" get hot enough to burn oil, and therefore the only two likely sources of contamination are water and metal shavings. The chamois will take care of the shavings. If the fluid is not cloudy or "milky" then it doesn't have water in it and he is home free. I suppose you could also use a time machine and go back far enough to buy some real GL3.
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