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Piston Engine Oils Explained

Piston Engine Oils (PEOs) have a high reputation throughout the general aviation community. Our partner AeroShell have been manufacturing and supplying PEOs for over 90 years, and these oils are used and trusted by more aircraft engineers and pilots than any other brand.

There are two main types of PEO: NON-DISPERSANT MINERAL OILS and ASHLESS DISPERSANT OILS:

Non-dispersant mineral oils (straight single grade oils)

  • Blended from high viscosity index (HVI) base stocks;
  • Do not contain additives except for a small amount of pour-point depressant and an anti-oxidant;
  • Grades must be selected and changed to suit the climate (temperature);
  • Available in Grades 65, 80, 100 and 120;
  • Used for the break-in process on new or recently overhauled engines. This helps the piston ring and cylinder wall mate together and create a good gas seal;
  • Approved to SAE-J-1966 (formerly MIL-L-6082E).

Ashless dispersant single grade oils

  • Blended from HVI base stocks and nonmetallic additives to give exceptional stability, dispersancy and antifoaming properties;
  • Used for the normal operation of all four-stroke aviation piston engines;
  • Grades must be selected and changed to suit the climate (temperature);
  • Approved to SAE-J-1899 (formerly MIL-L-22851D);
  • Available in Grades W80, W100 and W120, as well as W80 Plus and W100 Plus;
  • AeroShell Oil W80 Plus and W100 Plus are premium single-grade oils containing the standard additives of ashless dispersant oils plus an anti-wear additive, a corrosion inhibitor and a metal passivator. These advanced additives provide extra protection against corrosion, rust and wear.

Selecting the correct grade

The AeroShell straight and W series oils should be selected and changed to suit the climate.

For example, an aircraft operating primarily in the Middle East should generally use a 120 grade oil, while a European aircraft would use either 80 or 100 grades.

To mitigate this in fluctuating climates, AeroShell have developed AeroShell Oil W 15W-50, an all season, ashless dispersant oil.

  • A semi-synthetic blend of high-quality mineral oil and more than 50% synthetic hydrocarbon base stock, plus the ashless dispersant additive system;
  • Used in certified four-stroke aircraft piston engines;
  • All-season oil, no seasonal or climate-related changes needed;
  • The synthetic base stock component provides better low-temperature pumping for quicker lubrication of all engine parts after start-up and in low temperatures;
  • The mineral base stock helps to disperse lead by-products that could form lead sludge;
  • The blend of mineral and synthetic base oils makes this oil more thermally stable so that it deteriorates more slowly, i.e., retains its performance for longer than single-grade oils made of 100% mineral oil;
  • Could help to reduce fuel and oil consumption compared with single-grade oils;
  • Outstanding corrosion and wear protection for excellent engine cleanliness;
  • Approved to SAE-J-1899 (formerly MIL-L-22851D).