First, I don't have time right now to write a lot, I'll get back with something later, but here are the basics...1- First of all, to sum it up, John(UK) is correct. 15W-30 (or 15W-40, or even others like 20W-50, 10W-40) can be substituted for GL-1... Why? read further... 2-GL-1 (Gear Lube - 1)is straight mineral oil. GL-5 (and others), even though they would better protect the gears from wear, they contain high pressure (HP) additives (sulphur, phosphorus, etc.) that are not compatable with copper containing materials in the machine, particularly when moisture can be present to form acid. 3-Motor oils do not contain these same high pressure additives because the combustion products leaking into the engine have moisture and would form acid if they were allowed. They DO contain additives (e.g. detergents, etc.) but not the HP additives. 4-SAE 90 (or 80) gear lube has about the same viscosity as SAE 30 to SAE 40 motor oil. The two standards are different. Although the measurement of viscosity has been made complex by modern engineering methods, it helps if you understand that the original use of the numbers were nominally the time in seconds to flow a given amount of oil through a specified hole at a given temperature. BUT THE TEMPERATURES WERE DIFFERENT FOR GEAR LUBE AND MOTOR OIL. Gear Lube was tested at 150F and engine oils were tested at 212F. So SAE 90 wt Gearlube, took 90 seconds at 150F and SAE 40 wt motor oil took 40 seconds at 212F. But if you tested SAE 40 motor oil at 150F, you would find that it took about 90 seconds, so therefore it would have been classified SAE 90 by the Gear Lube scale. 5- Multi-weight oils need more explaination, and I'll explain more later. But they do NOT get thicker as they get hotter... they still get thinner, but not as rapidly as single grade oils. SAE 10W-40, SAE 90 GL, SAE 20W-40, all have approximately the same viscosty at 212 F. At temperatures greater than that they will all be thinner. From thickest to thinnest (T>212) 10W-40, 20W-40, SAE 90 GL (not a typo...) So at temperatures less 212 F, the order is reversed, thickest to thinnest (SAE 90 GL,20W-40, 10W-40) More later, maybe... Jim
|
