The best four-stroke engine oil not only protects your vehicle’s engine but also helps your car run more smoothly.
We researched and tested dozens of options, evaluating them on performance, quality, and value. Our top choice, YamaLube All Purpose 4 Four Stroke Oil, offers maximum protection and performance.
Here is the best four-stroke engine oil.
Best Four Stroke Engine Oil: Editor Recommended
Our Editor’s Best Four Stroke Engine Oil Reviews
- SAE 10W-30 MOTOR OIL FOR SMALL ENGINES: One 32 fl oz bottle of STP Premium Synthetic Blend 4 Cycle Small Engine Oil SAE 10W-30, formulated for small engines in lawnmowers, generators, tractors, snow blowers, and other outdoor power equipment
- ALL-WEATHER FORMULA: This 4 cycle engine oil is a synthetic blend with an all-weather formula that promotes easier starts all year and can be used in all seasons
- FIGHTS THERMAL BREAKDOWN: Antioxidants fight thermal breakdown to enhance oil durability, helping the SAE 10W-30 oil handle high temperatures without losing its effectiveness
- REDUCES ENGINE WEAR AND OIL CONSUMPTION: Anti-Wear Technology minimizes engine wear, while the viscosity index improver helps reduce oil consumption and provides consistent lubrication at a wide range of temperatures
- PREVENTS BUILDUP: Detergents help keep small engine components clean and control carbon deposits, preventing buildup that can affect performance and start-up
- 50% stronger wear protection to meet the extreme heat and higher RPM demands of 4-stroke marine engines
- Up to 8X better rust defense. Running or stored, your marine engine takes in moisture. Left unprotected this exposure can lead to severe rust damage
- Engineered specifically for the unique demands of marine motors
- Premium full synthetic formula for performance and durability in extreme conditions
- Direct replacement for Mercury Marine 8M0078628
- Designed for use in 4-stroke marine engines
- Formulated to provide superior corrosion resistance and wear protection to maintain peak engine performance and reliability
- Special viscosity modifiers help to optimize the performance of high-rpm 4-stroke outboard motors
- 25W-40 viscosity
- 50% stronger wear protection to meet the extreme heat and higher RPM demands of 4-stroke marine engines
- Up to 8X better rust defense. Running or stored, your marine engine takes in moisture. Left unprotected this exposure can lead to severe rust damage
- Engineered specifically for the unique demands of marine motors
- Premium full synthetic formula for performance and durability in extreme conditions
- Genuine OEM Factory Original Equipment Lubricant
- For use in Mercruiser Inboard & Sterndrive engines
- For use in Mercury Verado outboard motors
- Superior corrosion protection
- Most recommended OEM marine engine oil
- Superior ATV and UTV engine protection protecting critical internal moving parts from the wear and tear of sudden starts and stops
- Formulated to maximize power and minimize wear in high-revving 4-stroke engines
- Cleaning agents and dispersants prevent deposits under severe conditions
- Viscosity improvers resist film breakdown and maintain its performance
- Superior wet clutch protection helps ensure maximum power transfer and smooth shifting under high torque and loads
- Designed for use with all 4-stroke marine outboard motors and inboard and sterndrive engines
- Formulated to protect marine engines against corrosion and excessive wear
- Offers outstanding shear strength, viscosity retention and corrosion resistance
- 10W-30 viscosity
- Manufacturer part number 8M0078617
- Yamalube OEM Factory 4 Stroke All Purpose Oil
- Performance-Blend is Suitable for use in Motorcycles, ATVs, Side-by-Side Vehicles, and Scooters
- Mineral Oil Provides Stable Clutch Performance and Strength to Protect the Engine from Wear and Tear
- Oil Meets or Exceeds the JASO MA Requirements
- Genuine OEM Yamaha Product
- Up to 10X better friction protection vs. JASO T903:2016 friction std. and up to 5X better wear protection vs. industry standards in IVA engine tests
- Reformulated premium full synthetic with advanced technology and superior additives to maximize horsepower, acceleration, fuel efficiency and oil life
- Exceptional wet clutch protection helps prevent slippage for smooth shifting and maximum performance
- Enhanced protection against deposits and sludge that can reduce oil flow
- Meets or exceeds requirements of API SL and JASO MA-2 for 4-stroke motorcycles including Honda, Yamaha, Kawasaki, and Suzuki
- 1-Quart Bottle
- High Quality formual engineered specifically for small engines
- All season formula designed for operation in broad temperature ranges
- Zinc boosters reduce engine wear to extend engine life
- Optimized for use in Kohler and Honda Applications
Best Four Stroke Engine Oil Buying Guide
1. By Application: The first step is to determine the application of the engine you are choosing from by looking at the following points:
a. Air-cooled or water-cooled: An air-cooled engine is one whose cooling system is not immersed in liquid. These are the most widely used two-stroke engines and are generally found in small-scale applications. Water-cooled engines are the ones that are immersed in liquid and heat is dissipated through the liquid.
b. Stationary or portable: The next step is to determine whether the engine you are choosing is meant for stationary or portable use. The difference lies in the mounting points of the engine.
A portable engine has mounting points that are designed to allow it to be transported easily. On the other hand, the stationary engine has no such points, which means it cannot be moved.
c. High- or low-power: The next step is to determine the intended use of the engine so that you can choose one that meets your requirements.
If it will be used for heavy-duty applications, you need to choose an engine that is more powerful. On the other hand, if it will be used in light-duty applications, you can choose a smaller engine.
d. Single- or multiple-cylinder: If you are choosing a multiple-cylinder engine, it is important to determine the number of cylinders and their configuration.
An engine can have either in-line or opposed configurations. An in-line configuration has the cylinders aligned along a single axis, while in an opposed configuration, the cylinders are arranged in a V shape.
e. Reciprocating or rotary: The next step is to determine the type of motion of the engine you are choosing. A reciprocating engine, also known as a ‘piston’ engine is the most common type of engine.
It has a crankshaft at the center with connecting rods and a connecting rod with a piston. On the other hand, a rotary engine is one where the crankshaft is fixed with the engine housing.
There are two types of rotary engines: single-phase and two-phase. In a single-phase rotary engine, there is only one single rotor, while in a two-phase rotary engine there are two rotors and they rotate in opposite directions.
What else you should know about the best four-stroke engine oil
1. What are the benefits of using a four-stroke engine oil?
Four-stroke engine oil is designed to lubricate the engine, protect it from corrosion, and help to keep it clean. It also helps to improve fuel economy and reduce emissions.
2. What are the best brands of four-stroke engine oil?
The best brands of four-stroke engine oil include Castrol, Valvoline, and Mobil 1.
3. What are the differences between four-stroke engine oils?
The main difference between four-stroke engine oils is their viscosity or thickness. Thicker oils provide more protection for engine parts, while thinner oils allow the engine to run more efficiently.
4. How do I choose the best four-stroke engine oil for my vehicle?
The best four-stroke engine oil for your vehicle is determined by the manufacturer’s specifications.
5. What are the most common problems associated with four-stroke engine oils?
The most common problems associated with four-stroke engine oils are poor lubrication, sludge build-up, and oil leaks.
Conclusion
On the market, there is numerous best four-stroke engine oil. Hopefully, the list of the top ten best four-stroke engine oil will save you time researching and deciding on the best one for you.