GL-1 vs newer versions?

[MTMike]

I tried to get some GL-1 at NAPA yesterday, but the counter guy told me they haven't sold it for years and I should just get this GL-4 stuff instead. His claim was that it's the same as GL-1 just newer and better. Thoughts? Alternatives?

[76was124]

My NAPA store said the same thing, but found it in the back when I gave him the NAPA PN:.

This thread also gives some options http://fiatspider.com/f08/viewtopic.php ... gl1#p68356

[baltobernie]

Do not use GL-4 in your transmission. GL-1 can be ordered from our usual vendors, and most farm equipment dealers carry it. Personally, I'm liking Red Line MTL synthetic here in the cooler climate of the mid-Atlantic. Spring and Fall are our best Spider months, and the MTL is noticeably easier to shift.

[vandor]

[quote="baltobernie" Personally, I'm liking Red Line MTL synthetic here in the cooler climate of the mid-Atlantic. [/quote]

Redline says that their GL-1 equivalent is the MT90 lube, not the MTL, FWIW.

[RRoller123]

I use the MT90 and it does shift very smoothly.

[maytag]

Redline says that their GL-1 equivalent is the MT90 lube, not the MTL, FWIW.

FWIW:
Redline's documentation on the products indicate that MTL and MT90 are nearly identical products, with some viscosity adjustments only.
http://www.redlineoil.com/content/files ... 20Info.pdf

Red Line MTL is classified as a 75W/80W gear lubricant
satisfying the API Service requirements of GL-3 and
GL-4. MTL also satisfies motor oil viscosities SAE
5W/10W/30, and the viscosity requirements for ATFs.
MT-90 is a 75W90 GL-4 and also satisfies motor oil
viscosities SAE 10W/15W/40. The additive chemistry
used is non-corrosive, so even though they will provide
GL-4 performance, they will not corrode synchros or
bushings. Because of its low corrosivity, Red Line MTL
and MT-90 could also be used in transmissions requiring
GL-1 or GL-3 lubricants.

[majicwrench]

Get the right stuff, the napa guy is being lazy.
They can order it if they don't have it.
MTMike, you in Montana??
Keith in Libby

[divace73]

I remember reading somewhere that the 124 gearbox has brass or cooper based syncro's and a lot of EP oils have additives that eat them away and that is the reason to make sure you get the correct oil.
I wonder if the guy who says 'it's the same' will pay for the cost of a gearbox rebuild??
Can other's confirm this about the syncro's?

[maytag]

I remember reading somewhere that the 124 gearbox has brass or cooper based syncro's and a lot of EP oils have additives that eat them away and that is the reason to make sure you get the correct oil.
I wonder if the guy who says 'it's the same' will pay for the cost of a gearbox rebuild??
Can other's confirm this about the syncro's?

yes, that is correct. And GL4 is NOT the same spec as GL1. But Redline MTL and MT90 meet / exceed the GL1 spec, and are designed for "yellow metal" syncros, retainers, etc etc.

[MTMike]

Get the right stuff, the napa guy is being lazy.
They can order it if they don't have it.
MTMike, you in Montana??
Keith in Libby

Yup! Kicking around over in Helena