Thickest GL4 gear oil?

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Does anyone know who makes the thickest GL4 only gear oil? I know RP makes 85W140,but it`s GL4/GL5.
 
Btw... Most of the newer GL-5/GL-4 oils do not contain the sulphur that eats yellow metals if that's what you are afraid of.
 
Well,I`ve experimented a bit with my manual tranny. It shifts and operates 100% better with the thicker 85W90 over the 75W85 OEM oil. Shifting feel believe it or not is best on very cold mornings,when the oil is at it`s thickest,then gets a little notchy once it`s good and hot. With the 100F+ Texas summer getting closer,I`ve contemplated on trying the thickest oil I could get. I know Mobil 1 makes a 75W140 GL5,but they told me DO NOT use their gear oil in a GL4 spec`d manual transmission.
 
Originally Posted By: uconn1150
Which 85w-90 did you try?


Sta Lube 85W90 GL4. My car`s manual tranny has never felt smoother!!!!!!!!! 99% of the shifts are so smooth you can`t even feel the gears changing. Just get`s a tiny bit notchy once it`s completely hot,BUT,not all the time,just occasionally.
 
Originally Posted By: aquariuscsm
Originally Posted By: uconn1150
Which 85w-90 did you try?


Sta Lube 85W90 GL4. My car`s manual tranny has never felt smoother!!!!!!!!! 99% of the shifts are so smooth you can`t even feel the gears changing. Just get`s a tiny bit notchy once it`s completely hot,BUT,not all the time,just occasionally.


Where did you pick up the StaLube? PepBoys?
 
I agree with the GL-5 not in the tranny but with a GL-4/5 you should be fine. That means it does not have the sulphur that I spoke of earlier.
 
Originally Posted By: uconn1150
Originally Posted By: aquariuscsm
Originally Posted By: uconn1150
Which 85w-90 did you try?


Sta Lube 85W90 GL4. My car`s manual tranny has never felt smoother!!!!!!!!! 99% of the shifts are so smooth you can`t even feel the gears changing. Just get`s a tiny bit notchy once it`s completely hot,BUT,not all the time,just occasionally.


Where did you pick up the StaLube? PepBoys?


Got the Sta Lube at NAPA. I think it was around $17 for a 4 quart jug.
 
Originally Posted By: cosynthetics
I agree with the GL-5 not in the tranny but with a GL-4/5 you should be fine. That means it does not have the sulphur that I spoke of earlier.


It probably does have the sulphur, but it is well buffered.
 
RP claims that its EP additive in the GL-5 product is noncorrosive to gears and bearings. No claim is made as to protecting yellow metal synchros.

I am about to change the Karmann Ghia over to StaLube GL-4, as shifting seems to be a little rough with Castrol Hypoy GL-5 thats in there now. I thought the MT-1 rating makes it ok, but I found out that MT-1 only applies to non-synchro heavy truck transmissions. VW transaxles have spiral-bevel, not hypoid ring and pinion gears, so GL-4 is adequate.
 
Originally Posted By: Jimbo
RP claims that its EP additive in the GL-5 product is noncorrosive to gears and bearings. No claim is made as to protecting yellow metal synchros.

I am about to change the Karmann Ghia over to StaLube GL-4, as shifting seems to be a little rough with Castrol Hypoy GL-5 thats in there now. I thought the MT-1 rating makes it ok, but I found out that MT-1 only applies to non-synchro heavy truck transmissions. VW transaxles have spiral-bevel, not hypoid ring and pinion gears, so GL-4 is adequate.


Definitely give the Sta Lube a try. It worked wonders in my Z`s tranny! The GL5 rating does scare me a bit in the RP. I`m just afraid to introduce anything into an expensive transmission that could be the least bit harmful to it. I guess I`m just skeptical that a oil that has the additives to protect a rear diff will be gentle enough on the brass synchros in a transmission. Plus the limited slip in the Max Gear doesn`t seem like a good idea in a tranny. I may be dead wrong though.

I did read a post somewhere (not sure if it was here or another forum) where a guy used a 75W140 gear oil in a late 80`s Chevy truck manual tranny and that it made it shift like new again. He never listed the make of the gear oil he used though,and I can`t remember for the life of me where I read the post.
 
Amsoil just came out with a 190 wt. and a 250 wt. Don't know the ratings of these products.
 
Originally Posted By: Chris71
Amsoil just came out with a 190 wt. and a 250 wt. Don't know the ratings of these products.


Yep. GL-5. And a bit too thick I'm sure : )

It's meant for some really sticky situations.
 
No problem, glad I could help! I think I saw it at my NAPA before. Let me ask, have you ever tried Redline MT-90? That's what I have in my VW, and it's pretty nice, but I've always been tempted to try the Stalube, just never have since it's so thick when cold. Synthetic is typically more slippery, so I figured the dino lube might engage the sycros better.
 
Originally Posted By: glxpassat
No problem, glad I could help! I think I saw it at my NAPA before. Let me ask, have you ever tried Redline MT-90? That's what I have in my VW, and it's pretty nice, but I've always been tempted to try the Stalube, just never have since it's so thick when cold. Synthetic is typically more slippery, so I figured the dino lube might engage the sycros better.



Yeah,I tried MT90 once. It was ok,just seemed like the tranny got really stiff and notchy once it was good and hot. I was on TT.NET last night (Nissan Z forum) and a guy had just installed Redline Heavy Shockproof in his car (isn`t it something like a 75W250?) and he said his tranny has never felt better. He said he could even speed shift at 8000 rpm and it was smooth as could be. If anything,I`ll try the Sta Lube SAE140 and see what happens. And like you said about the dino fluid working better for synchro engagement,I read the very same thing on a Corvette forum.
 
Thanks, I bet you'll have to warm that 140 up under some hot water before it will go in! I may give the Stalube a try this summer if the Redline does that to me. Let us know how it goes!
 
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