GL-4 has sulphur in it (unless stated otherwise by the manufacturer), just not as much as GL-5. Therefore using GL-4 in our ancient trannies will still have a negative impact on the synchros, just not as fast as GL-5 will. And, yes, I admit to being cheap. My jug of GL-1 has been in the family for decades. 

Yes, GL-4 has a sulfur blend. It is included as a necessity in late transmissions. You must watch a lot of SUPERMAN SERIALS on the NOSTALGIC TV CHANNEL. You are in a time warp.

I think your family has been snortin' on that jug of mineral oil ...

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Again I rest my case. 😁  Sulphur is a necessity in LATE transmissions. It is NOT a necessity in our primitive boxes.

No time warp, I just won't use something that I know is harmful. If a manufacturer comes up with a modern formulation that does no damage I will use it...when my jug of GL-1 is empty. 

While you are resting your case -

https://www.redlineoil.com/mt-90-75w90-gl-4-gear-oil

Let me bring out this one factoid listed -



Not all lubricant refiners offer the exact same product. It is for you to read and comprehend.

API OIL CLASSIFICATION CHART -
https://www.oilspecifications.org/api_gos.php

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I'll take it under advisement when I run out of GL-1, but at $18.60 I can buy 2 gallons of Traveller. Hmmm, lessee. $18.60/qt. or 2 gallons of GL-1 for the same price. 🤨

I'll take it under advisement when I run out of GL-1, but at $18.60 I can buy 2 gallons of Traveller. Hmmm, lessee. $18.60/qt. or 2 gallons of GL-1 for the same price. 🤨

So let me get this right, you understand modern lubricants now but are unwilling to take car of that pretty MERC (which I assume has always been faithful) as you would rather spend your money on wine, women and song?

Interesting exercise ... Take it easy ...

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I have always understood that some modern lubricants are better than the stuff available when our cars were new. Modern motor oil is light years ahead of the sludgy, mostly paraffin based oils of the day, even though we have to mind the ZDDP levels and/or add it ourselves.. Modern differential oils are preferable and completely safe for us. Most modern transmission oils are not safe for the brass parts in our transmissions and I won't use them. The engineer in me just won't let me do it.

Well, I never thought I would get such a bundle of information. For what I sift, sulfur is bad for brass synchros and tractor supplies carry the oil I need. 

Glad to see you back. I thought maybe we scared you off. 

For what I sift, sulfur is bad for brass synchros and tractor supplies carry the oil I need. 

... sob ...

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