Quick, simple video on what those numbers mean on a bottle of oil! The single most important factor of a lubricating oil is its viscosity. There’s a long list of industry standard tests that an oil goes through to certify this rating (for anyone curious, this includes ASTM D5293, D4684, D445, and D4683) at both cold (-10°C to -40°C) and hot (100°C to 150°C) temperatures. Yep, even your uncle that’s always talking about how it’s -40°C, waaayyy colder than where *you* live, is considered. And thos