There are quite a few fluids in a vehicle that make sure that all systems are functioning optimally and smoothly. It is important to monitor the level of each one in order to keep the vehicle in good condition. Together with an expert, let's talk about the main tasks of transmission oil - what it's for and how often to change it. And let's also identify the best ones on the market in 2022

14 Top Transmission Fluid

Mentions:dextron iii, part number, backwards compatible, dexron iii, parts store
Mentions:good price, hard to find, drain and fill, transmission fluid, much smoother
Mentions:dexron in the gm transmission, oem fluid, delco, great price, compatible
Mentions:good price, power steering, cvt fluid, transmission fluid, good stuff
Mentions:highly recommend, dexron-vi full-synthetic, works great, tell the difference, lifetime fluid
Mentions:auto parts, every 30k miles, full synthetic, good price, maxlife atf
Mentions:cayenne turbo, oem fluid, cap, old fluid, works great
Mentions:mini cooper, manual transmission, gear oil, transfer case, give it a try
Mentions:manual trans, much better, mini cooper, fluid change, royal purple
Mentions:oil, mercon, changed, best price, maintenance
Mentions:exactly as described, great price, free shipping, real deal, fast delivery
Mentions:local dealer, great price, good stuff, great value, cheaper than the dealer
Mentions:gear oil, highly recommend, cheaper than at the dealer, take care, make sure

Oils have different compositions and properties because each transmission has different lubrication requirements. For this reason, fluids are divided into different classes:

  • mineral;
  • synthetic;
  • semi-synthetic.

Mineral oils are natural lubricants containing a mixture of hydrocarbons. They are the product of petroleum refining process.

They have a low viscosity index: at extremely high temperatures they thin out and give a thinner lubricating film. These oils are the most affordable.

Synthetic oils are man-made fluids that have been purified and broken down with chemical equipment. Because of this, they are more expensive, but the benefits justify the expense. Such oil has good thermal stability before high temperatures: it accumulates less silt, carbon or acids. Thus, its lifespan is increased.

And the absence of wax means that the oil is suitable for use at extremely low temperatures.

Classification of gear oils

Transmission oils have a basic class, which determines most of their qualities. At the moment, most of them are obsolete for use and only gear oils of GL-4 and GL-5 classes are used in modern vehicles. API classification provides for division mainly by the level of anti-seize properties. The higher the number of GL group, the more effective the additives providing these properties are.

GL-1 his class of gear oil is designed for operation under simple conditions without heavy loads. For agricultural machinery and trucks.
GL-2 Standard products designed for manual transmissions operating under moderate conditions. Differs from GL-1 oils with better anti-wear properties. Used for the same vehicles.
GL-3 These oils are used for manual transmissions where the qualities of GL-1 or GL-2 oils will not be sufficient, but they do not require the stresses that GL-4 oils can cope with. They are typically used for manual transmissions that operate under moderate to severe conditions.
GL-4 Designed for transmission units with all standard gear types that operate under moderate to heavy loads. It is used in modern passenger cars of various types.
GL-5 Oils used in harsh operating conditions, contain a variety of multifunctional additives with sulfur-phosphorus elements in the base. It is used for the same vehicles as

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