I bet most of the oils are the same with different packages.
You are exactly 99.999 percent right. It's all the same base oil, coming from a few different companies. They can refine it any way they like, into whatever group base stock that they'd like. But it's ALL coming from a handfull of oil compaines. And FWIW, in the USA, virtually any oil you can actually buy today can be labeled as conventional, semi-synthetic, synthetic blend, or synthetic oil, REGARDLESS of whether it's actually an "made" or "refined" base stock, and regardless of if it's a blend or one single base stock. What makes the difference, what makes oil do the magic it does, and the biggest cost of the oil, is the add pack.
The add pack comes from a handfull of companies. There are performance goals set by all kinds of manufacturers. Those are the material specifications that their engineers have laid out. You can meet those in multiple ways. Better base stock, cheaper add packs. Cheaper base stocks, and better add packs. Or better base stocks AND better add packs, OR...... You can get something made from almost a good enough base stock, or almost a good enough add pack, and label it as "recommended for" a particular material spec, or "meets or exceeds" some other add pack, when in fact it's not really there at all....
The website even shows opposite information then the label says when you actually see on the label at the store:
On Website:
"Employs a common sump to lubricate hydrostatic transmissions, differentials, wet brakes, hydraulics, and final drive gears"
"Engineered for use on a variety of farm equipment, off-highway machinery, industrial tractors, final drives, power take-off units, wet brakes, power steering units, and hydraulic systems"
That is my case right there. Tractor supply (and others) change oil suppliers on a regular basis, and many nation wide chains (I don't know about Tractor Supply on this issue), will have multiple suppliers. When an entity orders a house brand oil from "someone", it might be an existing off the shelf product, or it might be to their own specifications. If they're ordering from multiple blenders, it might not even be the same product, but being sold under the same product name. (In that case, it WILL have different SDS sheets, and the UPC will be different, but you'd have to check store to store to see who's selling what...)
Is Zinc content a difference that denotes AW or R&O oils?
"Zinc" is irrelevant. Zinc Dialkylid-phosephate somethingerother... Don't make me look it up... ZDDP is what the cool kids call it. The internet loves it, because it's a one layer deep thought process, and WAS one of the most common "last line of defense" defenses built into the add pack. It's also the cheapest way to achieve a "last line of defense". And quite consumable. If you're actually using that feature of a particular oil, the "zinc" gets "used up" quite quickly. It was not banned, it was not "outlawed", it was not taken away or reduced by our government in any way. It has been reduced though, but for other reasons. The bulk of manufacturers who make things expensive enough to have a material spec for their oils (in any application, engines, transmissions, hydraulic components, etc) have written their specs, changing over time to keep up with the modern expectations of lower maintenance, longer drain intervals, etc, which leads to oil evolving past zinc. The replacement "last line of defense" additives are not a one layer deep thought process. But it's not so easy to spot in modern oils of any kind, as it's not a one line, one chemical entry on a data sheet. And in the case of wear on moving, interacting metal bits... It's not a "wear" additive. The "last line of defense" protection comes in when something goes horribly wrong. The wear we're discussing, normal wear and tear, with oil circulating and being present and in place as it should be, the "zinc" doesn't apply there, it just floats around happily still in the oil, waiting on hat one (hopefully isolate) incident where the boundry layer becomes compromised.
Enough venting about the Internet's love of "Zinc". The answer to that question about zinc in hydraulic oils is "probably not", depending on who and how the add pack was made. No oil "causes" rust or oxidation. In a "hydraulic oil", without other listings, other applications, R&O, or "rust and oxidation" is a circulating oil that has added additional rust and oxidation protection, up to "somebody's" set level of protection. Who's that somebody? Well, there's minimum standards, but if it's got ANYBODY's actual approvals "Approved for", "Meets", etc, it's way more so than any minimums for the use of that term. If it's got "Recommended for", Suitable for", Meets or Exceeds", all bets are off. This doesn't mean that R&O doesn't prevent wear, as it absolutely does. It's served a lot of hours in a lot of places, and made quite a name for it's self.... AW oils are "anti-wear" hydraulic oils. That lable will include R&O, and it will reduce wear in some more demanding test beds. Nothing huge, we're not talking about stuff that's a challenge here. Both of these are a long way from "space age" technology. (And let me point out that "space age" was 60 years ago)... But neither job description is high tech, high demand, or really anything "too challenging". We have plenty of modern boutique oils now, as specially engineered fluid solutions to lazy and/or cheap mechanical design and manfuacturing practice. (I'm thinking light automotive engines right now, but it's starting to show up all over the place....) So the AW "might" include some, or even a bunch of last line of defense stuff, such as the zinc. Or it might not. But the stuff you see as last line of defense in an engine doesn't really apply much in a gear box. Neither is under any obligatioin to have much of any of that type of protections, although either, if they're meeting a component maker's spec, will be protected in some way from minor breakdowns of the boundry layer, maybe by zinc, more likely by other means. I honestly doubt that your lathe has enough load on any of the gears to actually "activate" a zinc package anyhow. Another note, The AW doesn't imply that R&O causes or fails to prevent wear, just that in tests for conditions that would warrant AW, AW will pass any given wear test with less wear, when compared to a non AW hydraulic oil, such as R&O. In lesser demand testing, such as R&O applications, I'm pretty confident that you'll find variable results as to whether AW allows less wear or not, when it's under less demanding conditions. It won't be worse, but it doesn't "necessarily" shine brighter until it's stressed more..
TRAVELLER® Premium Anti-Wear Hydraulic Fluid ISO 46 (SAE 20 Equivalent) is a high quality hydraulic oil that is specifically formulated to protect against rust, corrosion, foaming, oxidation and meets or exceeds the requirements for industrial and mobile hydraulic systems, Including; Sperry Vickers M-2950-S and 1-286-S, Denison HF-0, HF-1 and HF-2, Cincinnati Milacron P-68, P-69 and P-70, DIN 51524-3 and ISO 11158 HM.
This product is not recommended for transmissions, differentials, wet brakes or final drive gears.
"
Are there any clues here?
I am really learning a lot about oils that I never knew before from this conversation!
Bernie
The clue I get from here is this- It "Meets or exceeds" is a legal way of implying stuff meets a spec. If they say it MEETS sperry vickers M2950S, then it HAS TO MEET that material spec. If it says it "MEETS OR EXCEEDS a material spec, especially if it has "qualifiers" like "for industrial and mobil hydraulic systems", it's the same marketing wank you see all over the place... Meets or exceeds is NOT the same as "meets". And who determined what parts of M2950S apply to whatever the oil maker determined to be "mobile". And what is there determination between "industrial", and what else? Commercial, Residential, Agricultural... Who else makes hydraulics? Which ones did they or did they not include. So what I read from that is it might be probably kinda in the ballpark of the right stuff for that spec, but it's wrong enough to get them sued if they said "THIS STUFF MEETS M2950S.
To truly understand this stuff, the whole entirety of the internet (indluding myself) will be unable to help. Eight or more years of degrees get you an entry level job, and with twenty or thirty years in the field, you're still struggling to keep up... If your head is spinning, don't feel bad, I'll promise you that my head is spinning faster. Hence why I offer my opinion that the best answer is NOT to try to pick out the absolute minumum protection that's suitable, not to decide if a cheap and convenient product is gonna work good enough, but to determine that here's something that's reasonably well available, at a not terribly inflated price, that will not leave you wondering when you find a worn, sticky, scored part, or any other thing that might go worng with a lubricated part, "could this be an oil problem"? My opinion is that you should never have that question, even if chit just blows up in your face. AW and R&O are easy specs to hit, and don't have all the crap that you don't need and cant use, including (I might have said this) mosture management that's appropriate to a cold sump, and don't have additives that can themselves oxidize over time, leading to a host of other issues over the course of time. Engine oil being the absolute worst in that department, but multipurpose tractor fluids do rely on getting warmed up regular. Not near so hot as engine oils, but pretty near boiling anyway.
So like I say, while many, many people report success, I don't know exactly what they have for oil, I don't know their exact climate, I don't know the use case or duty cycles, and really, I don't know a lot of things to use such reports as "data" with any kind of meaningfulness. Even though I fully believe (mostly) all of those reports to be accurate, they're not well enough defined to be counted as "data" to base a decision on. So I choose to use name brand stuff that's not cheap, because I use very little. but were I using a volume that made it impractical for me to pay that much extra for that, and I wanted a generic fluid that left me with no questions, I would more than likely be price shopping, but in the circulating oil category, without "extras", more based on lil and less based on the add pack, which puts me in the AW or R&O category. No multipurpose fluids, no engine oils, etc. And because those are easy enough to come by, and because relatively speaking, compared to premium quality (or just highly marketed) products, they're priced pretty well, that's probably as far as I'd go. Splitting hairs about which purpose built fluid can be used successfully off label just doesn't, to me, make up for the time it takes to get current, accurate information.
If you really, really, absolutely have zero choice but to get the absolute cheapest thing that there is because you need ten pails of oil to fill your gearbox, and you think it is actually worth the time to chase down current, accurate information-
Get a freaking barrel from a proper oil supplier, they'll give you that stuff!! Find who's selling 303 fluid. It's an obsolete (meaningless, unmanaged, unenforced, abandoned specification that was based on whale oil... so everybody's take on it today is different, you've got to pick a brand/part number first, then research it... It's kinda borderline OK for some things.... In large quantities, you might be able to save enough (in my estimation) to be worth the effort... For just a pail or two.... Just hydraulic oil is really the safe option. Not (Absolutely not) the only option, just my take on the cost/effort/risk/comfort zone equation.