Gear oil differences GL-3 vs GL-5

bonjo · Jul 21, 2002

Getting ready to change the oil in my AX-15 manual transmission. My owners manual specifies gear oil w/ a GL5 rating, so I went out and bought 4 qts of Mobil 1 75W-90 synthetic. When I got home, I checked the service manual, and it says use oil with a GL-3 Rating. Hmmm. There's a conflict here.

Anybody know what the difference is between these two ratings? Or why the service manual and owners manual differ? Did Chrysler change their minds at some point? Does it matter? I saw a straight gear oil on the shelf that was rated for both GL-3 and GL-5, but it was an off brand

John

5073 · Jul 22, 2002

bonjo,

Don't use a GL5 rated fluid in your AX15!! This must be a misprint in your owner's manual.

A GL5 fluid contains EP (extreme pressure) additves. These additives are corrosive to the soft metals in your tranny. Your tranny life with be reduced with the use of this type of gear oil.

A GL3 fluid does not contain these additives....hence, it is soft metal "friendly."

Your best bet is to use one of the following:

1. Mopar branded GL3 gear oil.

2. Pennzoil Syncromesh (the bottle should have the Mopar spec number on it)

3. Redline Oil MT90 Gear Oil

I would not use the no-name brand. Generally, no-name brands use a lesser base oil and additive package to be price competitive.

4242 · Jul 22, 2002

I have a 2002 and the service manual asks you to use a GL-3 Lubricant

bonjo · Jul 23, 2002

Yeah, It's kind of strange, I know, but I'm sitting here looking at my '99 Wrangler owners manual. It says:

"Manual Transmission Fluid
Recommended Fluid
Use only Mopar Gear Lubricant or equivalent SAE 75W-90 APA-GL5 grade."

If I hadn't have looked at my FSM, I wouldn't have caught it. Went out and picked up a gallon of Redline MT-90 today and changed it out.

Thanks everyone for the help.

5073 · Jul 23, 2002

Hey bonjo,

Do you notice if your shifts are any smoother with the Redline in??

bonjo · Jul 23, 2002

I've only driven it once since making the switch, but I can't say I notice a difference. Having said that, I must admit that I never had any complaint prior to the change. I've heard some people complain about hard shifting, but mine's always been fine. One other thing. I've only got 10,000 miles on my '99. I changed the fluid only based on the calendar. Maybe with higher milage I'd have noticed a difference.

I always figure with the money I'm saving on labor, I can afford the very best lubes.

Best Regards,
John

5073 · Jul 23, 2002

I appreciate the reply. I have heard great things about the Redline MT90. After a couple thousand miles, I have heard the tranny will shift like butter.

I have about 10,000 on my '01, and will be switching out in the next 5000 miles or so.

Happy jeepn', bro.......

Bob J · Jul 23, 2002

I thought the safer fluid was just a requirement of the NV-3550 found in '00s and newer?

smunns · Jul 23, 2002

My AX5 was grinding pretty bad, so I changed the fluid to Redline MT90. After the change it seemed to grind worse than it did before, but after about 50-100 miles, it shifts a smooth as butter, and the grinds have gone away!

I highly recommend redline!

4924 · Jul 23, 2002

good thing i checked out this thread. About a week ago i changed my tranny lubricant and used GL-5 cuz thats what it said in my repair manual. It recomends GL-5 in the differentials also. Does anyone know if i should use GL-3 there as well?

B

5073 · Jul 23, 2002

Use a good quality GL5 in your pumpkins....there are no soft metals to worry about. You definately want an Extreme Pressure lubricant in there.

If you have the limited slip in the rear, make sure you purchase some additive for it.

Even better, many GL5 gears oils are designed for use with a limited slip rear end, and have the additive built in.

Gear oil differences GL-3 vs GL-5

bonjo

5073

4242

bonjo

5073

bonjo

5073

Bob J

smunns

4924

5073

Top Contributors this Month

Recommended Communities