GN4 is Honda’s mineral-based conventional oil built for low-heat, everyday riding. The HP4 series steps up with synthetic blends and full synthetics designed for higher stress. It includes variants such as HP4S and HP4M. HP4S is fully synthetic, engineered for maximum performance and extreme temperatures.
HP4M includes molybdenum (moly), a friction-reducing compound that boosts fuel economy and peak horsepower in high-heat racing applications. Choosing the correct oil matters because most Honda motorcycles and ATVs use a shared oil sump design. The same oil lubricates your engine, transmission, and wet clutch simultaneously.
Honda GN4 vs HP4: Which Oil Should You Buy?
The GN4 and HP4 oil series differ significantly in base composition, intended use, and performance characteristics. These oils power Honda’s entire Powersports lineup.
Honda Pro Honda GN4 Motor Oil
GN4 runs in everyday bikes like the Grom and Navi, sport quads like the 300EX and 400EX, utility ATVs across the complete TRX range (especially the FA series), and side-by-sides like the Pioneer 500 and Pioneer 1000.
Honda Pro Honda HP4 4-Stroke Motor Oil 10W-40
The HP4 series covers similar ground but scales up for performance applications. HP4S (full synthetic) works in ATVs, UTVs, motorcycles, PWCs, and scooters. HP4M (synthetic blend with molybdenum) is made exclusively for Honda scooters like the Forza and PCX. Standard HP4 (synthetic blend without moly) is approved across all Honda Powersports products, while HP4RU (full-synthetic racing oil) is backward compatible with bikes requiring 10W-30 or 10W-40.
Honda Pro HP4S Full Synthetic 4-Stroke Motor Oil
GN4 is a mineral/petroleum-based conventional oil. It’s Honda’s original 4-stroke formula, dating back to 1975. GN4 doesn’t typically contain molybdenum (moly) as a primary additive. HP4 (semi-synthetic) is a synthetic/mineral blend developed to combine the strengths of synthetic and mineral oil.
Honda Pro Honda HP4M Synthetic Motor Oil
The standard HP4 does not contain moly, making it safe for wet clutches. The HP4M variant contains moly for friction reduction but is restricted to dry-clutch applications like scooters (PCX, Forza). HP4S (full synthetic) is the “Crown Jewel” of Pro Honda Oils, engineered for maximum performance. It does not contain moly.
Use GN4 if you’re breaking in a new engine or riding in normal, low-heat conditions. It’s Honda’s proven formula for everyday use and costs less than the HP4 line.
Use HP4 (synthetic blend) if you’re riding in normal to moderate conditions and want better protection than GN4 offers. The synthetic blend provides greater shear stability and oxidation resistance. Use HP4S (full synthetic) if you’re pushing your bike hard in extreme temperatures or high-performance situations. It’s the best protection Honda offers but comes at a premium price.
Use HP4M only if you own a Honda scooter like the PCX or Forza that specifically calls for it in the manual. Never use HP4M in motorcycles or ATVs with wet clutches because the molybdenum will accumulate on clutch plates and accelerate slippage.
Alternatives to HP4 and GN4
Honda GN4 or HP4 (non-moly versions) are not always easy to find and tend to be more expensive. That’s why many riders look for a Honda GN4 oil equivalent that adheres to the JASO MA standard while offering better availability and value.
Mobil 1 Racing 4T 10W-40
Mobil 1 98JA11 10W-40 Racing 4T Motorcycle Oil
Mobil 1 Racing 4T 10W-40 is an aftermarket full synthetic motorcycle oil that meets the JASO MA2 specification required by Honda for wet-clutch motorcycles. This oil works as an alternative to Honda’s GN4 and HP4 oils, though it’s formulated specifically for high-performance applications rather than general use.
ExxonMobil engineered this oil with enhanced detergent and dispersant additives to combat deposit formation in high-heat conditions. The JASO MA2 certification confirms wet-clutch compatibility, preventing the slippage issues you’d see with automotive oils containing friction modifiers.
Also compatible with:
- Any four-stroke motorcycle requiring JASO MA or MA2 specification
- Air-cooled and liquid-cooled motorcycle engines
- Integrated transmission and wet-clutch systems
Liqui Moly 4T 10W-40 Street
Liqui Moly 4T 10w-40 Street
Liqui Moly 4T 10W-40 Street is an aftermarket fully synthetic motorcycle oil that meets JASO MA2 specifications, making it compatible with Honda GN4 and HP4 applications. This oil works in any four-stroke motorcycle with or without a wet clutch where current API SP or JASO MA2 specifications are required.
Liqui Moly engineered this with a Total Base Number of 7.0 mg KOH/g, providing adequate acid-neutralizing capacity for extended drain intervals. The 10% Noack evaporation loss is moderate for a 10W-40, meaning you’ll see predictable oil consumption in air-cooled engines. Sulfate ash content sits at 0.8 g/100g, keeping it safe for catalytic converters.
Also compatible with:
- Any four-stroke motorcycle requiring API SP or JASO MA2
- Wet and dry clutch systems
- Air-cooled and liquid-cooled engines
- Motorcycles with catalytic converters
Motul 7100 10W-40 4T
Motul 7100 4T 10W-40 Synthetic Oil 4 Liters (104092)
Motul 7100 10W-40 4T is an aftermarket fully synthetic motorcycle oil that meets JASO MA2 specifications, making it compatible with Honda GN4 and HP4 applications. It uses Motul’s Ester technology combined with synthetic basestocks for enhanced film strength in high-performance engines.
The ester additives improve clutch engagement and reduce internal friction losses compared to conventional synthetics. Motul optimized phosphorus and sulfur content specifically for catalyst-equipped motorcycles, preventing emissions system degradation. The API SP certification provides enhanced oxidative stability and deposit control beyond older API ratings.
Drain intervals can extend up to 16,000 km depending on manufacturer recommendations and riding conditions.
Also compatible with:
- Four-stroke motorcycles requiring API SP or JASO MA2
- Wet and dry clutch systems
- Catalyst-equipped motorcycles
- ATVs, UTVs, side-by-sides, PWCs, and snowmobiles per manufacturer specs
Royal Purple HPS 10W-40
Royal Purple Synthetic Motor Oil with Synerlec Additive Technology
Royal Purple HPS 10W-40 is an aftermarket fully synthetic motorcycle oil that meets JASO MA2 and ACEA E9-16 specifications, making it compatible with Honda GN4 and HP4 applications. This oil is formulated with elevated zinc/phosphorus levels and Royal Purple’s Synerlec additive technology for aggressive street and light competition use.
The elevated zinc/phosphorus content protects against valve-train wear in engines with aggressive camshafts or high valve-spring pressures. Synerlec technology increases oil film strength beyond conventional anti-wear additives, reducing metal-to-metal contact and friction losses. The Total Base Number of 9.9 mg KOH provides strong acid-neutralizing capacity for extended drain intervals.
Royal Purple positions HPS as a performance-upgrade oil rather than an OEM-specification product, meaning it prioritizes protection over emissions-system chemistry restrictions.
Also compatible with:
- Gasoline and diesel engines (automotive and motorcycle)
- Turbocharged and supercharged applications
- Wet clutch motorcycle transmissions
Shell Rotella T6 15W-40
Shell Rotella T6 Full Synthetic 15W-40 Diesel Engine Oil
Shell Rotella T6 15W-40 is an aftermarket fully synthetic heavy-duty diesel oil that meets JASO MA2 specifications, making it compatible as an alternative to Honda GN4 and HP4 oils in motorcycles. This oil is primarily formulated for diesel engines but carries JASO MA and MA2 certifications for wet-clutch motorcycle applications.
The 15W-40 viscosity is thicker than Honda’s typical 10W-40 specification, which means slightly reduced cold-flow characteristics but potentially better protection in high-temperature or high-load conditions. This makes it suitable for riders in warmer climates or those running older, high-mileage engines where bearing clearances have increased.
The oil meets API CK-4 and ACEA E9 specifications, with extended drain capability in diesel applications, though motorcycle drain intervals should follow manufacturer recommendations.
Also compatible with:
- Four-stroke motorcycles requiring JASO MA or MA2
- Heavy-duty diesel engines (primary application)
- Wet clutch systems
- Allison transmissions (TES-439)
Comparison of GN4 and HP4
| Oil | Viscosity Grade | Base Oil | Pour Point | Best For |
|---|---|---|---|---|
| Mobil 1 Racing 4T | 10W-40 | Full Synthetic | -48°C | High-performance sport riding, air-cooled engines, track use |
| Liqui Moly 4T Street | 10W-40 | Full Synthetic | -32°F (-18°C) | General sport/street use, catalyst-equipped bikes, balanced performance |
| Motul 7100 4T | 10W-40 | Full Synthetic + Ester | -30°C | Sport/adventure riding, aggressive use, modern catalyst-equipped engines |
| Royal Purple HPS | 10W-40 | Full Synthetic | -48°C | Modified engines, high-stress applications, elevated zinc needs, competition use |
| Shell Rotella T6 | 15W-40 | Full Synthetic | -39°C | Older high-mileage bikes, warm climates, heavy-duty use, budget option |
JASO and API Standards
An oil’s suitability for a Honda Powersports vehicle is its compliance with two key technical standards: JASO (Japanese Automotive Standards Organization) and API (American Petroleum Institute).
JASO MA/MA2 Standard for Clutches
JASO MA is the original standard. It meets the basic friction requirements for wet clutch operation. Choose this for older models or vehicles where this is the only spec listed in the manual.
JASO MA2 is a higher-specification standard that meets a more stringent friction test. It’s preferred for modern, high-performance engines because it ensures even better, more precise clutch grip under high stress and heat.
Most modern, high-quality motorcycle oils (including the HP4 series and synthetic alternatives like Shell Rotella T6) carry the JASO MA2 rating.
API Service Classification and Oil Quality
Every owner’s manual specifies a minimum API Service Classification (like API SG, SH, SJ, or SL). This rating is a global standard that indicates the oil’s overall quality, performance, and additive package.
The API class ensures the oil has the necessary detergents, anti-wear agents, and stability to protect the engine’s internal components. Each letter increase (from SG to SL, for example) denotes a newer standard and improved performance.
Honda’s engines typically require a minimum of API SG or higher. Both the Pro Honda GN4 and HP4 series meet and often exceed the current required API service levels.
When choosing an alternative oil, always confirm it meets both the specified JASO MA/MA2 rating and the required API service class in your owner’s manual.
Closing Notes
The choice between GN4 and HP4 is an investment decision: are you optimizing for cost or ultimate protection?
GN4 is the proven, dependable standard. Switching to an HP4 semi-synthetic or full-synthetic base offers protection that better resists the modern engine’s greatest stressors: heat and shear. This stability translates directly to longer component life and more consistent power delivery over extended use.
The only true compatibility issue in the Honda lineup is the friction modifier in HP4M, which turns a performance booster into a clutch killer in the majority of their vehicles. Use the JASO MA/MA2 and API ratings as your final checkpoint. Never trust a price tag or a brand name. Trust the certified standards to keep your shared sump happy and your clutch grabbing precisely.
If you’re overwhelmed by the choices, give Shell Rotella T6 a try. Rotella T6 has earned a cult following among riders who appreciate its high zinc content, strong detergent properties, and the fact that it’s JASO MA2 certified despite being marketed as diesel oil. Just be aware that some bikes are picky about it. While most riders report smooth shifting and clean engines, a few models (particularly certain Triumphs and Daytonas) seem to prefer motorcycle-specific oils.
Shell Rotella T6 Full Synthetic 15W-40 Diesel Engine Oil
