Glossary of Engine Oil Terms

Chemical compounds added to base oils to enhance their properties and performance.

Additives that form a protective layer on metal surfaces to reduce friction and wear in engines and other machinery.

Additives that slow down the oxidation process of the oil, extending its useful life and preventing the formation of harmful deposits.

A lubrication regime where the oil film is very thin and there is some contact between surface asperities, relying heavily on anti-wear additives.

The presence of unwanted substances in oil, such as water, fuel, coolant, or wear particles, which can degrade oil performance and engine health.

Lubricants refined directly from crude oil, offering basic protection for engines under normal conditions.

Additives that protect metal surfaces from chemical attack by forming a protective barrier or neutralizing corrosive substances.

Additives in motor oil that help keep engine parts clean by preventing deposit formation and removing existing deposits.

Additives that keep contaminants suspended in the oil to prevent sludge formation and deposits.

A form of hydrodynamic lubrication that occurs in non-conforming contacts under high pressure, such as in gears and roller bearings.

Motor oils designed to provide protection for extended oil change intervals, often featuring enhanced oxidation resistance and cleaning properties.

Additives that form a protective layer on metal surfaces under high-pressure conditions, preventing welding and reducing wear.

Additives that reduce friction between moving parts, improving fuel efficiency and reducing wear in engines and other machinery.

Motor oils made entirely from synthetic base stocks and high-performance additives, offering superior protection and longevity compared to conventional oils.

Specially formulated motor oils designed for vehicles with high mileage (typically over 75,000 miles), containing additives to address age-related engine issues.

A lubrication regime where a thick, continuous oil film completely separates moving surfaces, providing optimal protection.

The ability of an oil to resist chemical breakdown in the presence of water, maintaining its properties and performance.

Oil that meets the viscosity requirements of two different SAE grades, providing effective lubrication across a wide temperature range.

An oil analysis is the process of examining a sample of used oil to assess engine condition, oil condition, and contamination levels.

The rate at which an engine uses or loses oil, often measured in miles per quart or kilometers per liter.

The breakdown of oil molecules over time due to heat, oxidation, and contamination, reducing the oil's ability to protect and lubricate the engine.

The ability of an oil to maintain a protective layer between moving parts under high pressure and temperature conditions.

The chemical reaction between oxygen and oil molecules that leads to oil degradation, increased viscosity, and the formation of harmful deposits.

The ability of an oil to resist oxidation, maintaining its properties and performance over time.

The ability of an oil to interact with engine seals without causing them to shrink, swell, or degrade, preventing leaks and maintaining engine integrity.

A blend of conventional and synthetic oils, offering a balance between performance and cost.

The ability of an oil to maintain its viscosity under high stress conditions, crucial for protecting engine components.

Oil that meets the viscosity requirements of only one SAE grade, typically used in specific applications or older engines.

A thick, dark deposit formed in engines from oil oxidation and contamination, which can clog oil passages and reduce engine efficiency.

Motor oils that combine synthetic and conventional base stocks, offering a balance between the performance of synthetics and the cost-effectiveness of conventional oils.

Lubricants made from chemically modified petroleum components or non-petroleum materials synthesized in the labratory, offering superior performance compared to conventional oils.

The degradation of oil due to high temperatures, leading to changes in viscosity and the formation of deposits.

A hard, amber-colored coating that forms on engine parts due to oil oxidation and polymerization, reducing heat transfer and engine efficiency.

A fluid's resistance to flow, crucial for determining an oil's ability to protect engine components at various temperatures.

An international standards organization that develops and publishes technical standards for a wide range of materials, products, systems, and services, including those related to lubricants and motor oils.

A unit of dynamic viscosity in the centimeter-gram-second (CGS) system of units. Water at 20°C has a viscosity of 1 cP.

A unit of kinematic viscosity in the CGS system. It's equal to 1 mm²/s in SI units.

A test that measures an oil's viscosity at low temperatures, simulating cold engine starts. Lower CCS viscosity generally means easier cold starts. Performed using ASTM D5293 - Standard Test Method for Apparent Viscosity of Engine Oils and Base Stocks Between −10 and −35 °C Using the Cold-Cranking Simulator.

Also known as absolute viscosity, it's a measure of a fluid's internal resistance to flow under an applied force. Often measured using ASTM D2983 - Standard Test Method for Low-Temperature Viscosity of Lubricants Measured by Brookfield Viscometer.

The temperature at which oil vapors will continue to burn for at least 5 seconds after ignition by an open flame, typically a few degrees higher than the flash point. Also measured using ASTM D92.

The lowest temperature at which oil vapors will ignite when exposed to a flame, an important safety parameter and indicator of the oil's volatility. Determined by ASTM D92 - Standard Test Method for Flash and Fire Points by Cleveland Open Cup Tester.

A measure of an oil's resistance to foaming and its ability to release entrained air. Excessive foaming can lead to oil starvation and increased oxidation. Tested using ASTM D892 - Standard Test Method for Foaming Characteristics of Lubricating Oils.

A test that measures the wear preventive characteristics of a lubricant by rotating a steel ball under load against three stationary steel balls immersed in the test oil. Conducted using ASTM D4172 - Standard Test Method for Wear Preventive Characteristics of Lubricating Fluid (Four-Ball Method).

API classifications for base oils. Group III are highly refined mineral oils, Group IV are PAOs, and Group V includes all other synthetics like esters.

A measure of oil viscosity under conditions similar to those in an operating engine, crucial for maintaining oil film thickness and protecting engine components. Measured using ASTM D5481 - Standard Test Method for Measuring Apparent Viscosity at High-Temperature and High-Shear Rate by Multicell Capillary Viscometer.

A measure of a fluid's resistance to flow under gravity, typically measured at 40°C and 100°C for engine oils. Determined using ASTM D445 - Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids.

A measure of oil evaporation under high temperature conditions. Lower NOACK volatility indicates less oil consumption and better high-temperature performance. Determined by ASTM D5800 - Standard Test Method for Evaporation Loss of Lubricating Oils by the Noack Method.

A type of synthetic base oil known for its excellent thermal stability, low volatility, and good low-temperature properties.

A measure of concentration often used for trace elements or contaminants in oil. 1 ppm is equivalent to 1 mg/kg or 0.0001%.

The lowest temperature at which oil will flow, crucial for cold weather performance. Measured using ASTM D97 - Standard Test Method for Pour Point of Petroleum Products.

SAPS refers to the content of sulphated ash, phosphorous and sulfur in motor oil, most commonly in European manufactured vehicles. Low SAPS oils are designed to be compatible with emission control systems in modern vehicles.

An older unit of kinematic viscosity, representing the time in seconds for 60 mL of oil to flow through a calibrated orifice at a specific temperature.

Total Acid Number is the measure of the acidity of oil, indicating the level of oxidation and degradation. Lower TAN is generally better. Measured using ASTM D664 - Standard Test Method for Acid Number of Petroleum Products by Potentiometric Titration.

A measure of the oil's reserve alkalinity, indicating its ability to neutralize acids formed during engine operation. Higher TBN generally means better protection against corrosion. Determined by ASTM D2896 - Standard Test Method for Base Number of Petroleum Products by Potentiometric Perchloric Acid Titration.

Analysis performed on used oil to assess its condition, detect wear metals, and determine if it's still fit for use.

Analysis performed on new, unused oil to establish a baseline for its properties and additive content.

A measure of how much an oil's viscosity changes with temperature. A higher viscosity index indicates less viscosity change with temperature, which is desirable. Calculated using ASTM D2270 - Standard Practice for Calculating Viscosity Index from Kinematic Viscosity at 40 °C and 100 °C.

A common anti-wear additive in motor oils that provides protection against metal-to-metal contact, especially during engine start-up.

An Authorized AMSOIL Dealer is an individual or business approved by AMSOIL to sell their products and represent the brand, often receiving training and support from the company.

An additional oil filtration system that works in conjunction with the engine's full-flow filter to provide finer filtration and extend oil life.

An AMSOIL customer who purchases products at retail pricing without the benefits of Preferred Customer or Dealer status.

The earnings an AMSOIL Dealer receives based on the sales volume of their Personal Group and their own direct sales.

The earnings an AMSOIL Dealer makes from the sale of AMSOIL products, typically the difference between their wholesale cost and the selling price.

AMSOIL's line of high-efficiency oil filters, designed to provide superior filtration and engine protection.

An AMSOIL product line designed to meet the basic performance requirements of vehicle manufacturers, suitable for normal service conditions.

An AMSOIL fuel additive designed to clean fuel injectors, intake valves, and combustion chambers, improving engine performance and efficiency.

In the AMSOIL business structure, refers to the network of dealers and customers directly or indirectly sponsored by an individual dealer.

AMSOIL's Preferred Customer program offers wholesale pricing, exclusive promotions, and other benefits to loyal customers who frequently purchase AMSOIL products.

A designator in the AMSOIL system for customers who have made qualifying purchases and are eligible for certain benefits or discounts.

The highest level of achievement in the AMSOIL Dealer program, representing top-performing dealers with significant sales and team-building success.

The standard price for AMSOIL products when purchased without any special customer status or discount program.

AMSOIL Signature Series is their premium product line, offering the highest level of protection and performance for demanding applications and extended drain intervals.

In the AMSOIL business model, the act of bringing new dealers into the AMSOIL network, often providing mentorship and support.

Discounted pricing offered to AMSOIL Preferred Customers and Dealers, allowing them to purchase products at lower than retail prices.

An AMSOIL product line designed to provide extended drain intervals and enhanced protection compared to conventional oils.

AMSOIL's proprietary technology designed for high-performance and racing applications, offering superior protection under extreme conditions.

An organization that defines performance standards for motor oils used in European vehicles.

An ACEA specification for high-performance oils suitable for gasoline and diesel passenger car engines with extended drain intervals.

An ACEA specification for catalyst-compatible oils with mid-SAPS (Sulphated Ash, Phosphorus, and Sulphur) levels, suitable for vehicles with diesel particulate filters and three-way catalysts.

A system that defines the performance level and application of motor oils, using letter codes (e.g., SN, SP) to indicate the oil's suitability for different engine types.

A diesel engine oil specification introduced in 2016 for high-speed four-stroke engines, designed to meet 2017 on-highway greenhouse gas emission standards.

A specialized diesel engine oil specification introduced alongside CK-4, specifically for certain high-speed four-stroke engines designed to meet 2017 on-highway greenhouse gas emission standards.

An API classification introduced in 2018 to address low-speed pre-ignition (LSPI) issues in turbocharged gasoline direct injection engines.

The latest API classification for gasoline engine oils, introduced in 2020, offering improved high temperature deposit protection and more stringent sludge control.

A urea-based fluid used in selective catalytic reduction (SCR) systems to reduce NOx emissions in diesel engines.

A designation given by API to oils that have passed specific tests for fuel economy improvement in gasoline engines.

General Motors' proprietary oil specification, designed to meet the specific needs of GM gasoline engines, with dexos1 Gen 3 being the latest version.

Oils specifically formulated for use in heavy-duty diesel engines, typically meeting API CK-4 or FA-4 specifications.

A joint organization of U.S. and Japanese automobile manufacturers that develops minimum performance standards for motor oils.

The latest ILSAC specification for motor oils, introduced in 2020, providing improved fuel economy, engine protection, and compatibility with ethanol-containing fuels.

A subset of the GF-6A specification, specifically for 0W-16 viscosity grade oils used in certain high-efficiency engines.

A Japanese Automotive Standards Organization specification for two-stroke engine oils, indicating basic performance level.

A Japanese Automotive Standards Organization specification for four-stroke motorcycle engines, ensuring proper clutch performance in wet-clutch applications.

Refers to the original producer of a vehicle or engine, often used in the context of manufacturer-specific oil specifications or recommendations.

Oils formulated for use in passenger car and light truck gasoline engines, typically meeting API SP and ILSAC GF-6 specifications.

An API designation similar to Energy Conserving, but including additional requirements for emission system protection and turbocharger protection.

A classification system developed by the Society of Automotive Engineers to rate motor oil viscosity, using numbers like 5W-30 or 10W-40. The number before 'W' indicates low-temperature viscosity ('W' stands for winter), while the number after represents high-temperature viscosity.

A National Marine Manufacturers Association (NMMA) specification for two-stroke cycle gasoline engine lubricants used in water-cooled outboard engines.