8/19/2023 0 Comments Low viscosity oil meaning![]() ![]() Also used in dog boxes and with suitable additives in limited slip differentials. GL-5 – Containing many more additives than GL-4 oils, GL-5s are used to create gear oils with extreme load resistance, protecting systems such as hypoid gears such a differential. This is typically used for synchromesh gearboxes and transaxles. GL-4 – The most common base oil grade, the oils of which contain good volumes of extreme pressure additives. GL-1 to GL-3 = mostly aimed at road use for light load applications. Gear oils are also classed under a GL ( Gear Lubricants ) rating. Again, additives will help as covered below. For motorsport use the ideal is to have low viscosity for low drag and transmissions losses but enough film strength to protect the gearbox or differential. Multigrade SAE gearbox oil grades include two numbers separated by a ‘W’ (75W140, for instance), with the initial number before the ‘W’ indicating performance at 0☌ and the number after showing the lube’s performance at 100☌.Īs with engine oils, the higher the number, the greater its viscosity. Interestingly a 90-grade gear oil viscosity falls between a 40 or 50 grade engine oil, and 80 grade gear oil is similar viscosity to a 20-grade engine oil. The higher numbers of a gear oil (e.g., 75W-140) do not mean that it has higher viscosity than an engine oil. The SAE has a separate viscosity rating system for gear, axle, and manual transmission oils, SAE J306, which should not be confused with engine oil viscosity. Most of these engines will benefit with a swap from a monograde to a multigrade that will cover the range of both grades. Classic competition cars can also take advantage of the massive advances in oil technology, engine building, and the improved quality of engine components. It is common for 1950’s or earlier engines to have a monograde oil specified in a single viscosity, one for winter and another for summer. These additives will be covered later in the blog. However clever uses of additives in many oils mean a thinner oil can be often used with no loss in protection, or a standard weight oil can have much less friction than a basic budget oil of the same rating.Ĭare should be taken if changing the viscosity too far if the engine has variable valve timing, as the oil pressure can be too low to operate the timing system. However, for competition use the engine will run much hotter regardless of the ambient temperature so the higher viscosities listed are generally advised. It must be remembered the car manufacturers recommended viscosity is aimed at road use, and usually has a several viscosities for different climates / ambient temperatures. A low viscosity will also mean less power loss due to oil drag (sometimes a lower viscosity is used for qualifying before going back to the normal oil viscosity). The motorsport monograde oils can be very effective if used in the correct operating temperature but tend to have very specific applications.įor motorsport use the ideal is to have easy and good flow characteristics to prevent damage on cold start up but very high film strength to maintain clearances at extremely high temperatures found in the competition. Some older / classic oils are referred to as a monograde and have a single viscosity rating such as 40 or 50. Thick, high viscosity oils are typically better at maintaining film strength to protect engines at high temperatures. Thin, low viscosity oils give better protection to engine parts at cold temperature. Engine oil viscosity is important, oils naturally thicken as they cool and thin as they are heated. A 5W-30 will flow easier than a 10W-30 at start-up temperatures and a 10W-30 will flow more easily than a 10W-40 at normal engine operating temperatures. The smaller the number, the better it will flow. The second number is defined by how an oil flows at normal engine operating temperatures. This measurement is related to how an oil flows when it is cold, such as at engine start-up. The first number precedes the letter ‘W’ which stands for Winter. There are two numbers that define viscosity meaning. This is determined by the volume of oil to flow over a set time (think of the difference in time filling a cup with water compared with custard) The Society of Automotive Engineers (SAE) has established a numerical code system for grading engine oils according to their viscosity characteristics known as SAE J300. The viscosity of an oil is measured by its resistance to flow. Viscosity is the most common parameter to choosing the correct oil. Oil Viscosity Grades Explained Engine Oils We have compiled this competition oils guide to cut through some of the jargon and help choose the most suitable lubricant for your motorsport car. A typical bottle of engine oil or gear oil can have a rather bewildering list of standards, grades and terms that can be confusing if you are unfamiliar with them.
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