Zinc vs Brass

[rotorwrench]

Thanks for the info Uncle Bob. That's the first I've seen for a revision to the SAE gear lube specs. I'd much rather go with a system I can remember even though I'm slowly getting a grasp on the "new systems".

Kerby

[Special Coupe Frank]

Lubricants have been "evolutionary", just like the machinery itself.

Prior to petroleum-based lubricants, oils and greases were usually obtained from animals (Whale oil, beef tallow) or certain plants ( Castor bean ).

Systems for measuring the viscosity of lubricants have also been evolutionary... for some time, it seemed that SAE was the "ultimate" standard here in America, but there seems to be a shift towards ISO over the last 10 years.

The "heavy gear oil" used prior to the Depression was ( or was derived from )
Steam Cylinder Oil. Somewhere along the way, this became known as 600-weight or 600 W oil. The data sheets from Lubriplate, Mobil, and other mfrs seem to place "600 weight" oil somewhere around SAE 250 on the viscosity scale.

This oil is very "sticky", and tends to cling to gears, cylinder walls, slide valves and such, AND, tends to be better contained by primitive felt / leather seals...

Just for fun, ask a Model T guy about using SAE 90 / 140 in the rear-end of a Model T...

I believe the caution against using EP lubes in the Borg-Warner OD is because back in that era (1940's - 1960's ), most EP lubes had a high sulfur content, and this was bad for the "yellow metal" inside most gear-boxes of that period.

In my area, all the parts houses / lube distributors look at me like I have four heads when I ask for any gear lube heavier than SAE 140...
Really didn't expect to find 600, but I got the same blank look when I asked for SAE 250 gear oil...

When I get some extra cash, I will be ordering a 5-gallon pail of Lubriplate SPO-299.

[Uncle Bob]

Reader warning don't bother reading the rest of this if you're averse to geekish lubrication stuff. None of this is intended to embarass anyone, be argumentative, or start a war. Just trying to clarify misunderstandings that seem to persist in spite of prior efforts. All of what will be said is fact based not opinion (unless flagged as such), and in no way is all inclusive of what is known about the subject. None of this will improve your sex life (if you still have one), increase the size of your retirement account, or make your kids stop trying to move back in.

Frank makes a good point about things evolving, and in lubricants the wheel never has stopped turning. But some basics still remain the same. Viscosity is the most important characteristic of a lubricant, not the only characteristic, just the most important. Viscosity can be said to be a measure of rate of flow. If you look at any specification sheet or technical data (e.g. the link I posted above) you will NEVER see the word WEIGHT used by the professionals in reference to viscosity (in conversation they may go there for the sake of communicating with the non-professional). Most often you'll see the term GRADE used. Why? Because most viscosity grades are defined by institutions aimed at specific markets. For example, SAE is the Society of Automotive Engineers, aimed at things automotive. AGMA is the American Gear Manufacturers Assoc., and they serve the industrial gear world. ISO, International Standards Organization, doesn't serve the interests of a specific industry, but rather attempts to support systems of communication for technical data so that whereever a piece of equipment (for example) ends up, the user can find (in this discussion) a lubricant to serve the need. ASTM, American Society for Testing and Materials, is another similar organization that publishes standards so that different disciplines can work to a consistent procedure when describing a product or process. To help mentally process that, imagine the chaos if various bolt manufacturers didn't follow a standardized thread pitch. Standards are an absolute necessity in an industrialized world.

Okay, enough with the background stuff, and on to specifics related to comments in this thread.......I warned you this was geekish.

SAE still defines lubrication grades for automotive, have for approximately 100 years. Their grade numbers are mostly arbitrary, and specific to them as definitions. But the underlying methods of determining what physical viscosity underlies or defines, say an SAE 30, are based on standards published by ISO and/or ASTM. They're not exclusive, they work together for communication consistency sake.

Rant alert!!! What's with the W thing!!?? No, not the obsession with constantly demonizing a former POTUS, I mean the willy-nilly use of the letter w and the word weight. Remember the remark above about how the word weight was NEVER used by professionals? Well, most here aren't professionals so can be excused. But if your buddy was going around calling every woman he met a SLUT because he thought it was a compliment, wouldn't you want to straighten out his thinking? Well, unless you're a sadist.

I know, the notion of weight projects the idea of the thickness, and as most of you have learned, as you age your waist thickens and the scale shows you weigh more. In oils, the bigger the viscosiy number on the container the slower it pours at room temperature, ergo, the bigger the number the more it must weigh.....I get it, but it ain't weight it's viscosity, and viscosity is rate of flow, and rate implies time, not pounds/grams etc.

Back to the W thing. Most often (yep, 600w is the exception) when you see W behind a viscosity number it means WINTER not weight. You've learned that temperature affects the rate at which oils flow, generally (yes there are a few exceptions but that's outside our interests here) they get thinner as the temp goes up. So, in winter we are concerned about how well the lubricant flows, so it can do it's job, so what the w means is there is a standard measure for low temp flow. Otherwise, the standard measure for engine and gear lubes is done at 100c (metric, that International Standard thing). I'll post a chart below on viscosity cross references, and you'll note the w is only on the "lighter" grades (a concession to understanding on my part). Yup, because those are the ones that are appropriate for temps during what we define as winter. Notice on the "heavier" (I'd really prefer to say "more viscous") grades there is NO w.

Then there's that pesky 600w exception. Again, the W does NOT mean weight. As Frank correctly noted, before petroleum lubes became dominant, animal fats were (and in some cases still are) used. 600w has been around since near mid 19th century, before automobiles were common. It's original intent was as a steam cylinder oil. The additive that made it effective in the wet environment of steam was whale oil (of course now verboten). So, what might you think a W in the description of a steam cylinder oil might mean? Yes, you in the back row.....correct.....it inferred the presense of whale oil. Give yourself a gold star.

Those of us schooled in tribology (look it up, I can't do everything for you) could go on forever on this stuff......................you've heard of the futility of trying to teach a pig to dance haven't you? And for both our sakes this is enough for this post. Hopefully this will help your understanding, the one or two of you that endured this far, or maybe it was not really important. Your call. Thanks for listening.