STP Semi Synthetic Motorcycle Oil 15W 40 is a multigrade engine lubricant designed for 4-stroke motorcycle engines. It combines mineral and synthetic base stocks with performance-enhancing additives to deliver balanced protection across a wide range of riding conditions — from daily commuting to spirited street riding.
This 946 ml (1 quart) bottle size is typical for motorcycle oil changes.

Key Characteristics

• Semi-Synthetic Formula: Blends traditional mineral oil with synthetic components to improve performance over conventional oils. Semi-synthetic oils generally offer better thermal stability, reduced wear, and longer life than straight mineral oils.

• Viscosity Grade — SAE 15W 40:

o “15W” indicates good flow at cold start temperatures (winter), helping protect engine parts quickly on startup.
o “40” indicates stable viscosity at normal operating (hot) engine temperatures.
This grade is commonly used in many motorcycles where the manufacturer specifies 15W 40 performance.

• Engine Protection: Formulated to help protect internal components from wear and corrosion, resist oxidation, and reduce deposit formation that could shorten engine life.

Typical Benefits

• Balanced Performance: Better protection than conventional oil with a more affordable price than full synthetic.

• Thermal & Viscosity Stability: Helps keep oil viscosity consistent across hot and cold conditions.

• General Use: Suitable for many 4-stroke motorcycles that call for 15W 40 semi-synthetic oil. Before use, always check your motorcycle’s owner’s manual for the correct oil grade and performance specifications (e.g., API and JASO ratings). (Industry standard descriptions of 15W 40 motorcycle oils often note performance for wear protection, cold start circulation, and deposit control.)