GL-1 Question

Just one more GL-1 question.

I called the company that makes or distributes the GL-1 oil I bought for my TO-35 and ask if the oil contained zinc.

The answer is no, no zinc in the GL-1 oil.

zinc is what makes the good diesel oil provide more Lubricity.

Question: should I add a supplement of zinc to my new GL-1 oil to help the gears and pump last a bit longer?

It isn"t just zinc that"s added to the oil. It also contains phosphorus. ZDDP was added to oil to help lube flat tappet cams and lifters and to prevent corrosion on lead/copper bearings. I can"t see any benefit to adding it to your GL1.

Thanks Jason,

I will not add the zinc supplement to my tractor hyd trans sump.

Rather than take it back is there anything else motor or trans wise that would benefit from a dose of zinc?

Lawnmower engines, bush hog gearbox, old jeep transmission, etc.

The additives in GL4 and GL5 oils, that GL1 lacks . . . don't just protect flat-tappet cam lobes and lifters. They also help protect hypoid gears by coating them with a sacrificial metal. GL4 or GL5 gives better metal-wear protection then GL1.

I doubt anyone can come up with a legitimate reason to use GL1 in a TO35 other then concerns of being "yellow metal safe." That being said, there are modern GL5s that ARE yellow-metal-safe.

If someone is privy to some other obscure reason for GL1 only in a TO35 - I'd like to hear it. GL1 90W is basically the same as 30W or 40W SAE non-degertent SAE motor-oil. No additives and inferior metal wear protection as compared to GL4 and GL5. GL1 is the safest though when there is true concern for corrosion in brass or copper parts, or when wet brakes are involved. Wet brakes can plug from additives, but how many machines have them? Oliver HGs, OC3s, Terratracs and a few Case 310 crawlers?

Any older engine that has a flat tappet camshaft would benefit from a zinc and phosphorus or ZDDP additive, especially if you are running conventional oil in it instead of diesel oil. Most new camshaft manufacturers will not give you a warranty on new flat tappet camshafts unless you have proof of adding ZDDP additive to your oil during break in. So there's the proof that older engines need it and benefit from it.

The additive he was referring to was for engine oil. EP or extreme pressure additives in gear oil and AW or anti wear additives in engine oil are not quite the same. A legitimate reason to run GL1? Not all of us have easy access to yellow metal safe GL4 or GL5 hydraulic fluids,plus the fact that most modern hydraulic oils are around a 20 weight they do not work well in worn older style hydraulic systems that were designed to use a thicker hydraulic oil. I use GL1 in mine, if I were to change from GL1 it would be 10w30 or 10w40 engine oil as John(uk) has recommended on here and Ferguson had recommended years ago on the other side of the pond.

Additives like ZDDP or boron used in engine oils, or the "EP" type used in gear oils all use a sacrificial material to prevent metal wear.

SAE 30W-40W for engine oil is the same viscosity as SAE 90W oil for gear oil. They just happen to use different rating numbers.

Combo transmission/hydraulic oils are different then a 90W GL4 or GL5 gear oil. Using the engine-oil rating system - most are 20W IF for summer use, and 10W if for winter use (like Deere winter-grade Hyguard).

Friction Modifiers, Extreme Pressure additives, and Anti-Wear additives are all friction modifiers to one extent or another, but anti-wear additive films do not provide protection under long-lasting or sustained pressures, due to attrition. However, they will quickly reform providing enough additive reserve was included. So at times the delineation between AW and EP additives is not always clear and somewhat arbitrary. EP films, under extreme pressure, stay intact at higher temperatures and form/reform these films rather quickly after the pressure has passed. Most EP films also form at room temperature, unlike engine oil AW or FM additives. So we can say that the major differences between AW and EP films are that EP films:
a.) Form/reform more quickly
b.) Act or get to the base metal at room temperature, i.e., does not require
elevated pressures/temperatures to start the film reaction (the exception is the phosphate esters)
c.) Act as anti-galling, anti-welding additives
d.) Act/react when the pressures or loads are above what the AW additives can handle.
e.) AW additives form plastic films which "glide," whereas EP additives form films which shear or "slide"

As far as the 20w hydraulic oil, that's too thin for these older primitive hydraulic systems that use steel piston rings on the lift cylinder and no rings on the hydraulic pump pistons. Multiply that times 50 years worth of wear and tear on the pump and a thinner oil will cause more leakage and decreased performance of the lift. That would be like taking an engine that has 100,000 miles on it that was designed for 10w30 and suddenly start running 5w20 in it. You could do it but the engine wouldn't like it and you would have less oil pressure than before. Now in my newer tractors that have more modern hydraulic systems I use modern hydraulic oils.