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Message: [QUOTE="jimdawg185, post: 1195858, member: 757"] So, for the most part lubricants have tangible and intangible benefits. Many of these benefits are attempted to be replicated via testing procedures. This is where engineers and tribologists try and recreate the in service conditions to attribute certain qualities to lubricants. The most important thing a lubricant does is prevent wear. They do this by inducing what is called a full fluid film lubrication regime. There are basically two types of friction, dry and fluid. Dry is bad and fluid is good, basically. When a lubricant is involved there are three basic lubrication regimes.... Boundary, Mixed Film, and hydrodynamic (full film) or in non friction roller bearings elastohydrodynamic. Boundary would be similar to what our engines encounter when they are started after sitting all night long. There is little to no lubricant between the opposing surfaces. It might be hard to imagine, but all of the surfaces involved in bearing and journal surfaces (or just about any other surface for that matter) are no where near smooth. Every machined surface has an RMS (root mean square) rating that determines the surface roughness. Imagine a mountain range, RMS basically measures the centerline average between the peaks and valleys. During boundary regimes these peaks from each surface (asperities) are fully engaged. In most lubricants there are types of antiwear and EP additives that assist in limiting the amount of wear during this regime. Soon after the the surfaces begin to move in relation to each other a film begins to build up between the asperities and starts to separate them. This state is called mixed film lubricating regime. During this regime, the highest peaks of the asperities still make contact. Then, we encounter soon after (hopefully) full fluid film or hydrodynamic. If you want more info on this, google the Stribeck-Hershey Curve. One thing that helps me picture what is happening here is a surf board. Different shapes, loads, and speeds all effect how well a surf board stays above water. Too slow, no good... to heavy, no good... not fast enough, no good.... These things all play in the details that determine the OEM viscosity requirements of a lubricant, among other things that effect vis at the wide span of temperatures that a lubricant will encounter. Well, with that said.... Engine oils have their tests, trans fluids have their own. Then you have gear lubes. For the most part I will never put pre service lubricant tests above in importance to in service or post service. Lubrication Engineers always guarantees the performance of our lubricants post service, against any companies lubes of any cost. So I state the following with this in mind. The main tests, other than your common viscosity tests, for gear lubes are Timken, 4 ball wear, and FZG. For the most part, Timken is something that is important but can be a cheated in my mind. The test is difficult to manage because I can see some people putting the weight on fast, or slowly to effect the test. But, it is a standard test that most of the time can give you a good base of a lubricants ability to protect surfaces during boundary and mixed regimes. Our Timken on the Duolec gear lubes are really quite high, 75. Not too bad. The next one in line would be the four ball wear test. This test is a little more difficult to cheat on, but not impossible. The test still depends on a person placing weights on a load bar, but I don't see it making as much difference as it could on Timken. On the FBWT you have the weld point, where there is a total loss of lubrication of any kind and the balls in the test completely fuse together. Then you have the load, and wear scare measurement. Great tests that attempt to recreate the boundary and or complete loss of lubrication properties. For the most part they are testing the EP additives. These additives are activated by heat and pressure. Duolec has a 400 weld point with 77 kgf and a .33 wear scar. All very good test results where I have only seen one or two of our competitors beat us at, and those same lubricants will not beat us in any other test. Then you have FZG. In my mind this is the best test for trying to recreate an in service recreation of all three regimes. The test involves a gearbox, so it is the only test that actually measures wear on gears, which is nice for a gear lube. The test can actually involve many many different types of wear (of which I will not go into in an attempt to keep this not a day long read) There are stages that the test involves. And basically in the big picture the more stages that the lubricant passes the better and less wear that a lubricant allows during service. Most high quality gear lubes are around a 12, which is pretty good. But, our Duolec is 14+... Ive heard 16. But in all reality 14 is the final acceptable stage. The other important thing to keep in mind is that FZG attempts to recreate all the lubrication regimes, not just EP and antiwear during boundary. Granted, the case for hydrodynamic is tough because the lack of lubricant involved. But its much closer than any of the other tests available. So, the challenge.... is there another gear lubricant out there that makes it to 14+ in the FZG???? Where does your favorite gear lube make it too? We run our Duolec out to 400-500k miles in out OTR trucks with great success. Please let me know what you find.... and please ask any questions that you might have. [/QUOTE]