The Yellow Metal Debate

[chzuck]

Please move this if I selected the wrong place to post. Most tilling equipment utilizes gearboxes with worm drive and a brass gear is the major part of that gearbox. I have a 1981 Troy-Bilt Horse, which recommends an 80-90 or 140 weight gear oil. I would like to use 85-140. I have been using 140 GL-1 oil because in my area it is all but impossible to find a GL-4 gear oil. Everything I have seen is GL-5, which Troy-Bilt does not recommend. So, I hear both sides, some saying it does not matter, others saying definitely do not use a GL-5 oil. I would like to see some official, factual data one way or the other.

 

[Kira]

The sulphur compounds in GL-5 effect/corrode/destroy yellow metals or they don't, right?

 

[drtyler]

Many of the newer GL5 formulations are safe for yellow metals.

 

[jeepman3071]

The sulphur compounds in GL-5 effect/corrode/destroy yellow metals or they don't, right?

Many of the newer GL5 formulations are safe for yellow metals.

I have heard both of the above, for the last few years.

The last time I serviced an old Troy-bilt tiller, or anything I knew had yellow metals, I used a yellow metal safe oil, just to be on the safe side. It's not like they take a lot of oil, and you can still find GL-4 oil online pretty easily.

The AX-15 5 speed manual in my Jeep Wrangler has brass synchros that many claim can be harmed by yellow metals. I use Redline MT-90 in the transmission which is a GL-4 oil.

 

[drtyler]

I have heard both of the above, for the last few years.

The last time I serviced an old Troy-bilt tiller, or anything I knew had yellow metals, I used a yellow metal safe oil, just to be on the safe side. It's not like they take a lot of oil, and you can still find GL-4 oil online pretty easily.

The AX-15 5 speed manual in my Jeep Wrangler has brass synchros that many claim can be harmed by yellow metals. I use Redline MT-90 in the transmission which is a GL-4 oil.

My response is based on info from mfg. Its best to verify a particular product before using. Some products still use the older additive packages.


After pricing Sta-lube GL4 at local NAPA recently, I knew there had to be better options for the $.

 

[gman2304]

I used Sta-Lube GL4 SAE140 from NAPA in my 1961 vintage Simplicity Roti Cul tiller. Worked like a charm.

 

[jeepman3071]

My response is based on info from mfg. Its best to verify a particular product before using. Some products still use the older additive packages.


After pricing Sta-lube GL4 at local NAPA recently, I knew there had to be better options for the $.

Yeah I'm sure there are newer GL-5 oils that are fine, but I'd rather not ruin a piece of equipment because I didn't want to spend the extra couple bucks and time finding a GL-4.

That Sta-lube at NAPA is pricey! Definitely shop around online. Most of the parts stores are not worth going to anymore unless you need something right away, because the prices are much higher for the same stuff you can find cheaper online.

 

[chzuck]

The sulphur compounds in GL-5 effect/corrode/destroy yellow metals or they don't, right?

Yes, that is question with the somewhat elusive answer.

 

[jeepman3071]

Yes, that is question with the somewhat elusive answer.

Personally I don't trust it. It's possible that some GL-5 are safe, but I haven't seen a definitive answer on which are. Until then I will just continue to use GL-4 oils.

 

[Pablo]

Yes most all modern gear oils are brass, copper alloy safe

You can look up the test results for most gear oils. Called copper corrosion test:

https://www.amsoil.com/c/gear-oil/25/?zo=515729

I've been running the 75W-140 for years in my Troy-Bilt. Tiller doing great, but they sure use terrible seals, or rather the design is the seals wear in the dirt, nature of the beast I guess.

 

[Jetronic]

To my understanding, yellow metal safe means it won't corrode yellow metals. It does not however mean the EP additives will not have a stronger bond than the yellow metal itself, effectively ripping the gear apart every time the sacrificial layer gets worn off, resulting in accellerated wear

 

[benjy]

you are on-line + can find + buy most anything + have it delivered to your doorstep!!!!

 

[chzuck]

As long as I have a source near me for the GL-1 140, I will use that. Just trying learn what I can about this. I have written to one oil company, but in today's world, can their answer be trusted?

 

[Pablo]

As long as I have a source near me for the GL-1 140, I will use that. Just trying learn what I can about this. I have written to one oil company, but in today's world, can their answer be trusted?

Yes.

If you get to the right level. Of course some first level folks might - more or less accidentally or inadvertently or out of laziness - somehow give you a wrong answer. But there are none that I know of - of the top tier blenders - who will purposely lie about their gear oils.