Published in the February 2013 issue of “Die Porsche Kassette”

Another one of the neglected fluids in automobiles.  It must be that out-of-sight, out-of mind, because the gear oil in modern Porsches is set to be replaced every 90,000 miles.  Most modern Porsches aren’t even close to that mileage (with few exceptions).

First, all transmission fluid is not created equally.  There is a difference between the Automatic Transmission Fluid (ATF) used in automatic transmissions and Gear Oil used in manual transmissions, because the transmissions themselves are quite different, as you can see.

Manual Transmission (above

Tiptronic Transmission (below)

ATF is typically colored red or green to distinguish it from motor oil and other fluids in an automobile.  This fluid is a highly specialized oil engineered to perform in automatic and self-shifting transmissions.  It is typically a highly-refined hydraulic oil which must be made to conform to multiple tasks. In order to do so, special additives must be added, such as: anti-wear, rust and corrosion inhibitors, detergents, dispersants, surfactants, kinematic viscosity and viscosity index improvers and modifiers, seal swell additives and agents, anti-foam and anti-oxidation compounds, high-temperature thickeners, cold-flow improvers, gasket conditioners, pour point depressant and petroleum dyes.

On the other hand, GEAR OIL is a lubricant made specifically for transmissions, transfer cases and differentials in cars and trucks in other words, cars with manual transmissions.

Gear Oil is of higher viscosity to better protect the gears and generally has a strong smell of sulphur.  Most lubricants for manual gearboxes and differentials are hypoid gear oils.  These contain extreme pressure and anti-wear additives to cope with the sliding action of hypoid bevel gears.

You also have a choice between Synthetic and Dino Oils. Generally, synthetic gear oils are used whenever mineral oils have reached their performance limit and can no longer meet the application requirements; for example, at very low or very high temps, extremely high loads, or in extraordinary ambient conditions.

Synthetic lubricants continue to gain market share thanks to their higher performance properties that most often than not trump higher costs.

As in motor oil, the trick to getting the best out of your lubricant is by periodic changes based on time, mileage or continuous track use.

To learn more about Gear Oil, ATF and more, please visit my website at:

Happy Porscheing,

Ⓒ2013 Technolab /