FAQs

Q?

What is the warranty on WeatherTech® Products?

A.

All WeatherTech® products are guaranteed against faulty materials and workmanship for a period of three years from the date of purchase.

Exclusions to this warranty are wear through due to severe abrasive conditions, chemical contamination, such as spilled gasoline, bleach, etc. We are reasonable people and we believe in customer satisfaction. Depending on the situation, we will either replace your product at no charge or charge you a prorated amount for a replacement.

Q?

Can multiple AMSOIL gasoline fuel additives be mixed together with gasoline?

A.

Yes. AMSOIL fuel additives are compatible. When selecting a fuel additive be sure that it is the appropriate choice for the application. For specific product recommendations, contact Prolube Ltd at (868) 633-6110 or info@prolubecaribbean.com

Q?

Is it safe to use Engine and Transmission Flush in diesel engines?

A.

Yes. AMSOIL Engine and Transmission Flush helps restore operating efficiency, increase fuel economy and reduce emissions in both gasoline and diesel engines and automatic transmissions. Its potent, detergent-based formula dissolves and disperses sludge, varnish and deposits, promoting lower operating temperatures and reduced oil consumption.

Q?

What does the “W” represent in 5W-30 motor oil?

A.

The "W" in 5W-30 motor oil stands for "winter" and indicates the oil meets or exceeds certain criteria for good low-temperature performance. Motor oil with SAE viscosity grade 5W-30 behaves like an SAE 30 oil at high temperatures and SAE 5W oil at low temperatures, providing the necessary fluidity for rapid starts and efficient engine operation at low temperatures.

Q?

Can AMSOIL motor oils be mixed with other brands?

A.

Yes. AMSOIL synthetic motor oils are compatible with other conventional and synthetic motor oils. Mixing AMSOIL motor oils with other oils, however, will shorten the oil’s life expectancy and reduce the performance benefits. AMSOIL does not support extended drain intervals where oils have been mixed. Mixing other oils with AMSOIL motor oils may also void the AMSOIL limited warranty.

Q?

Must new cars be broken in using petroleum oil?

A.

No. AMSOIL synthetic motor oils can be safely used during break-in. In fact, many vehicles, including the Dodge Viper and Chevrolet Corvette, are factory-filled with synthetic oil.

Q?

Can synthetic oil be used in new engines?

A.

Yes. Synthetic oil is perfectly safe for use in both new and high-mileage engines.

Q?

What roles do additives play in motor oil performance?

A.

Most lubricating oils have other chemicals added to improve the overall performance of the fluid. Chemical additives are used to enhance the beneficial properties of the base oil or to make up for oil deficiencies. For passenger car motor oils, base oil makes up 70 to 80 percent of the final product; the other 20 to 30 percent is comprised of additive chemistry.

Additives help lubricants stand up to extreme operating environments. Even the best base oil would not be able to protect as well against the effects of heat, shearing forces, chemical and water dilution, corrosion and wear particles. In short, additives make good base oils even better. They give good base oils the performance benefits consumers have come to expect, such as multi-grade performance, extended drain intervals and extreme-pressure performance.

Anti-wear Agents chemically react to form a film barrier that prevent metal-to-metal contact and wear.

Antioxidants reduce the tendency for oil to react with oxygen and reduce sludge buildup.

Dispersants help suspend and disperse contaminants in the oil to keep engine surfaces free of sludge and deposits. They fight the build-up of corrosive acids and are most efficient at controlling low-temperature deposits.


Detergents help suspend and disperse contaminants in the oil to keep engine surfaces free of sludge and deposits. They are most efficient at controlling high-temperature deposits.

Extreme-Pressure Additives coat metal surfaces to help prevent close-contact components from seizing under extreme pressure. They are activated by high temperatures and high loads to react with the metal’s surface to form a sacrificial wear layer on components.

Foam Inhibitors reduce the surface tension of air bubbles and causes them to collapse.


Friction Modifiers can be used to give oil more 'slippery' characteristics. In engine oils, friction modifiers are used to increase the oil’s lubricity for the purpose of reducing friction and improving fuel economy.

Pour Point Depressants give high-viscosity oils good low-temperature properties. Pour point depressant polymers inhibit the formation of crystals to minimize low-temperature viscosity increase.

Rust & Corrosion Inhibitors form a protective barrier over component surfaces to seal out water and contaminants. While most rust and corrosion inhibitors work by forming a physical barrier, some rust inhibitors function by neutralizing acids.

Viscosity Index (VI) Improvers are long-chain polymers that help control the viscosity of multi-grade engine oils. They expand and contract as temperatures vary. High temperatures cause VI improvers to expand and reduce oil thinning; low temperatures cause VI improvers to contract and have little impact on oil viscosity.

Q?

What is the difference between synthetic and conventional oil?

A.

Motor oil, whether synthetic or petroleum-based, consists of molecular chains of hydrogen and carbon atoms, referred to as hydrocarbons. Petroleum crude oil is a thick, highly flammable dark-brown or greenish liquid with high energy density. Many contaminating elements exist in this complex mixture of hydrocarbons, including sulfur, nitrogen, oxygen and metal components such as nickel or vanadium. Petroleum crude oil is the raw material used for a wide variety of petrochemicals, including solvents, fertilizers, plastics and lubricants.

The oil refining process separates the various types of molecules in the oil by weight, resulting in a concentrated batch suitable for manufacturing products such as gasoline, LPG, kerosene or lubricant base oils. The chemical composition of conventional motor oil can vary substantially depending on the raw crude oil refining process.

While petroleum base oils are refined, synthetic base oils are manufactured and can achieve a higher performance level. Synthetic oil is chemically engineered for a certain molecular composition with a tailored and uniform structure. Such fine-tuned control over the final molecular composition of synthetic oils is the key to their superior performance properties. Designing molecular structures in a planned and orderly fashion results in molecules, and end-products, that are far more stable than their refined petroleum counterparts.

Q?

Can AMSOIL lubricants be safely mixed together?

A.

Applications require specific lubricant properties to deliver maximum performance and protection. AMSOIL carefully tailors its synthetic lubricants under the strictest quality control standards to provide the required properties for the intended application. Mixing AMSOIL synthetic lubricants is not only unnecessary, it may lead to reduced performance and even equipment failure.

Automatic transmission fluids offer a perfect example. Some transmissions require lubricants that contain specific frictional characteristics to reduce, or eliminate, clutch slippage, while other transmissions may require different frictional requirements. Mixing fluids recommended for different performance specifications may lead to a host of problems, including erratic shifting and transmission failure.

In some applications, mixing lubricants may not lead to equipment failure, but it will reduce performance. For example, if AMSOIL Signature Series 5W-30 Synthetic Motor Oil is installed in a vehicle, and its owner adds AMSOIL OE Synthetic 5W-30 Motor Oil to top off the engine if Signature Series isn’t available, the vehicle will continue to operate perfectly; Signature Series and OE Synthetic Motor Oil share a similar chemistry, and formulations of the same viscosity can be safely mixed. However, mixing lubricants will shorten Signature Series' life expectancy and reduce its performance benefits. AMSOIL does not support extended drain intervals where oils have been mixed.

To minimize the risk of performance- and warranty-related issues due to improper mixing, AMSOIL does not recommend mixing AMSOIL synthetic lubricants.