Is this NAPA gear oil GL-4?

Status
Not open for further replies.
Keep in mind that GL-4 is an obsolete spec, and that modern additives used to make a GL-5 gear oil are not harmful to the yellow metals in transmissions. If the label says the oil is OK in transmissions, it probably is OK.
 
Originally Posted By: Ken2
Keep in mind that GL-4 is an obsolete spec, and that modern additives used to make a GL-5 gear oil are not harmful to the yellow metals in transmissions. If the label says the oil is OK in transmissions, it probably is OK.


Yea and I can't say to use GL-5 it, but 5 to 10 years ago this subject was beaten to death here with one person known to know what was going on..stated that tests to certify GL-4 were not being done anymore and agreed with ken.

But if you look here:
http://corvaircenter.com/phorum/read.php?1,266128

It claims that that the GL-4 has half of the sulfur/phosphorous additive. This additive provides a stronger EP bond and it tends to bond to bras so strongly that it is ripped away (synchronizers) and caries brass away with it. It claims that much higher levels of brass are seen in Trannies that require GL-4 and use GL-5.

Probably prudence says to go with GL-4 if it is specified.
 
Last edited:
Originally Posted By: Ken2
Keep in mind that GL-4 is an obsolete spec, and that modern additives used to make a GL-5 gear oil are not harmful to the yellow metals in transmissions. If the label says the oil is OK in transmissions, it probably is OK.

Well, that makes things confusing again. I posted this question in regard to its potential use in a Nissan FS5R30A 5spd transmission in a '94 Hardbody. The FSM specifies GL-4, and there have been horror stories of gold flaked fluid draining out when GL-5 is used in this transmission. I would rather err on the side of caution and use a GL-4 fluid such as Redline MT-90 or Amsoil MTG.
 
For as little gear oil as is needed to change it out and not very often, I would also go for the real juice mentioned above and stay away from GL5 in a manual gearbox unless just temporarily or quick flush, or all that is available.
 
GL5 was always frowned upon due to the "upgrades" made to it that elevated it over GL4.Synchros couldnt take the additives over the long haul.I dont know if any changes have been made to "tame" GL5,but I would frankly stick with something like Redline manual trans fluid thats rated proper.
 
Gear oils with GL4 on the label aren't THAT hard to find ... Chevron 80W-90 is one. I believe Lubro-Moly 75W-90 is another and that brand is available in NAPA stores around here. Coastal used to put GL4 on their label (along with MT-1 and other certifications).

Of course, you can always go mail order with Amsoil and Red Line Oil gear oils, though they are a bit pricey ... but you don't need too much and don't have to do this very often.

Safest bet is to take your time and source a GL4.
 
I was at Napa yesterday, I looked at the one they had on the shelf, it said GL-3 GL-4 GL-5 on the back for certifications, seems to be a one lube fits all type, I would pass if your transmission/diff specifically wants GL-4.
 
Last edited by a moderator:
Just get either Amsoil MTG or Redline MT90. If you use a generic "gear oil" the shifting quality will be horrible. You want the manual tranny-specific add pack,not the rear diferential add pack. When my friend did a twin turbo motor swap in his Z32,he got everything bolted back up and realized he`d forgotten to fill the tranny,and just filled it with a generic GL5 80W90. Shifter was super hard to move and it would grind every gear.
 
When the mechanic replaced the axle on 2000 Maxima manual transmission, we lost at least a pint or more of GL-4. The mechanic asks me, "wow that is very clean fluid, when did you last change it?" My answer, "Never; that is factory fill!" The car has 172K miles.

Is there a place where I can relinquish my BITOG card? :)

- Vikas
 
Last edited:
Originally Posted By: aquariuscsm
Just get either Amsoil MTG or Redline MT90. If you use a generic "gear oil" the shifting quality will be horrible. You want the manual tranny-specific add pack,not the rear diferential add pack. When my friend did a twin turbo motor swap in his Z32,he got everything bolted back up and realized he`d forgotten to fill the tranny,and just filled it with a generic GL5 80W90. Shifter was super hard to move and it would grind every gear.


+1, Amsoil was the only quality MTF I could find for my '86 B2000 which also spec'd for the GL4. Previous fills were with generic Rotella 80W90 Gear Oil. As soon as the new fluid was in, I could tell a dramatic difference in the shifting from pulling it out of the shop. A very smart choice.
 
Status
Not open for further replies.
Back
Top