Selecting the right oil for your aircraft engine is one of the most important decisions you’ll make as an owner. The wrong choice can lead to accelerated wear, reduced engine life, and even engine failure. This guide covers everything you need to know about aviation oils.
Understanding Aviation Oil Grades
Aviation oils use a different grading system than automotive oils. You’ll see designations like W80, W100, and W120, where the “W” stands for “weight” (not “winter” as in automotive oils) and the number indicates viscosity.
Common Aviation Oil Grades
- W80: Lighter weight, often used in cold climates or for break-in
- W100: The most common grade for Continental and Lycoming engines
- W120: Heavier weight for hot climates or high-time engines
- 15W-50: Multi-viscosity, popular year-round choice
Straight Weight vs. Multi-Viscosity
The debate between single-grade and multi-viscosity oils has continued for decades. Each has advantages depending on your operating environment.
Single Grade Oils (W100, W80)
Single grade oils maintain consistent viscosity at operating temperature. Many engine manufacturers recommend single grade oils, and they’re typically required for engine break-in. They’re also generally less expensive than multi-viscosity options.
Multi-Viscosity Oils (15W-50, 20W-50)
Multi-viscosity oils provide better cold-start protection while maintaining proper viscosity at operating temperatures. They’re excellent for aircraft that operate in varying climates or see infrequent use where cold starts are common.
Mineral Oil vs. Ashless Dispersant
Mineral Oil
Straight mineral oil is required during engine break-in (typically the first 25-50 hours). It allows piston rings to properly seat against cylinder walls. Using ashless dispersant oil during break-in can prevent proper ring seating and lead to high oil consumption.
Ashless Dispersant (AD) Oil
After break-in, most aircraft transition to ashless dispersant oil. AD oils contain additives that:
- Suspend contaminants and carry them to the oil filter
- Reduce sludge and varnish formation
- Provide better corrosion protection
- Extend time between oil changes
Popular Aviation Oil Brands
AeroShell
AeroShell is the most widely used aviation oil brand worldwide. Their lineup includes:
- AeroShell W100: Standard single-grade AD oil
- AeroShell 15W-50: Popular multi-viscosity option
- AeroShell 100: Mineral oil for break-in
- AeroShell W100 Plus: Contains anti-wear additive LW-16702
Phillips 66
Phillips offers a complete line of aviation oils:
- X/C 20W-50: Multi-viscosity AD oil
- Type A: Single-grade AD oils
- Victory AW: Premium anti-wear formulation
Exxon/Mobil
Exxon produces the Elite series of aviation oils, offering both single and multi-grade options with advanced additive packages.
Oil Change Intervals
Most manufacturers recommend oil changes every 50 hours or 4 months, whichever comes first. However, oil analysis can help optimize your change intervals. Factors affecting intervals include:
- Flight frequency (more frequent flying is better)
- Climate and operating temperatures
- Engine condition and oil consumption
- Oil filter type (full-flow vs. spin-on)
Oil Analysis: Your Engine’s Report Card
Regular oil analysis is one of the best investments you can make. For about $30 per sample, you get detailed information about:
- Wear metals (iron, copper, aluminum, chrome)
- Contamination (silicon, sodium, water)
- Oil condition (viscosity, oxidation)
Trending this data over time reveals developing problems before they become expensive failures.
What Your Engine Manufacturer Recommends
Continental
Continental engines typically call for single-grade AD oil (W100 in most climates) after break-in. Multi-viscosity is approved but single-grade is preferred. Always consult your specific engine’s operator’s manual.
Lycoming
Lycoming approves both single and multi-viscosity AD oils after break-in. They specifically recommend their own brand (now marketed by Phillips 66) but approve equivalent products from other manufacturers.
Making Your Choice
For most aircraft owners, here’s a simple decision tree:
- New or overhauled engine: Use mineral oil until break-in is complete
- Year-round, moderate climate: W100 ashless dispersant
- Cold climate or infrequent flying: 15W-50 or 20W-50 multi-viscosity
- Hot climate or high-time engine: Consider W100 Plus or W120
When in doubt, consult your A&P mechanic. They know your engine’s history and operating conditions better than anyone. And whatever oil you choose, change it regularly—consistent maintenance is more important than brand selection.
Recommended Products
Based on our recommendations above, here are some of the most popular aviation oils and filters available. These products are trusted by aircraft owners and mechanics worldwide.
AeroShell Oil W100 Plus
The W100 Plus is an enhanced version of the classic AeroShell W100, featuring the anti-wear additive LW-16702. This additive provides extra protection against cam and lifter wear, making it an excellent choice for high-performance piston engines. Ideal for year-round use in moderate climates.
AeroShell Oil W 15W-50
For aircraft owners who fly in varying temperatures or don’t fly as frequently, the 15W-50 multi-viscosity is an excellent choice. It provides superior cold-start protection while maintaining proper viscosity at operating temperatures. Great for seasonal flyers and those in northern climates.
Tempest AA48110-2 Spin-On Oil Filter
Don’t forget the oil filter! The Tempest AA48110-2 is a popular spin-on replacement for many Continental and Lycoming engines. Quality filtration is essential for protecting your engine and extending oil life. Always change your filter with every oil change.
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