SAE 10W-40 motorcycle oil meeting API SG/SH or higher is recommended for the 1989 Honda FourTrax 300. Honda’s GN4 10W-40 is a common OEM choice. The engine oil also lubricates the transmission, and the typical capacity is about 1.8–2.0 quarts with a filter; follow the owner’s manual for exact figures and intervals.
Understanding the oil specification for the TRX300
The 1989 Honda FourTrax 300 uses a four-stroke engine that relies on a single oil fill to lubricate both the engine and the transmission. This means you should choose a straightforward, motorcycle-grade oil rather than a car oil, and you should select a viscosity that performs well in your climate. In practice, many riders stick with a 10W-40 grade and a conventional or synthetic motorcycle oil that meets API SG/SH or higher.
Recommended oil options
Below are oil options commonly used by owners of the TRX300. They are broadly compatible with the engine’s lubrication needs and are widely available.
- SAE 10W-40 motorcycle oil that meets API SG/SH or higher (e.g., API SN or higher is acceptable for newer climates and gear sets).
- Honda GN4 10W-40 motorcycle oil (a factory-recommended option for many Honda four-strokes).
- Any high-quality motorcycle-specific 10W-40 oil (conventional or synthetic) that clearly lists suitability for four-stroke engines with wet clutches and meets API SG/SH or higher.
When selecting oil, prioritize products designed for motorcycles and confirm they meet or exceed the API grade appropriate for older engine designs. Synthetic options are fine if you prefer them, but ensure compatibility with a four-stroke ATV clutch system.
Oil capacity and service notes
Know the typical oil capacity and how to perform a change can help you maintain the bike properly. The TRX300 uses engine oil that also serves the transmission, so you don’t need a separate transmission oil, but you should freshen the oil regularly to protect the antique engine.
- Warm up the engine briefly to loosen sludge and ensure accurate level readings.
- Position the ATV securely and place an oil drain pan underneath the engine drain plug.
- Remove the drain plug and allow the old oil to drain completely.
- Remove and replace the oil filter with a new one designed for the TRX300 if applicable.
- Install the drain plug with a fresh gasket or sealant as required and snug to the manufacturer’s specification.
- Fill with the specified amount of 10W-40 motorcycle oil, then check the level with the dipstick or sight glass as directed by the manual.
- Run the engine for a minute or two, recheck for leaks, and recheck the oil level after it settles.
Use the listed capacity as a guide, but always verify the exact oil capacity for your specific model year in the official Honda service manual or an authoritative service guide. Dispose of used oil responsibly at an appropriate recycling center.
Additional maintenance considerations
Because the FourTrax 300’s oil serves both engine and transmission lubrication, it’s important to stay on top of changes regardless of climate. In hotter conditions or heavy use, you might opt for a slightly higher-viscosity oil within the recommended range. In cold climates, a 5W-40 option may be acceptable if it meets API SG/SH or higher, but verify compatibility with the manual and avoid drastic deviations from the recommended grade.
Summary
For a 1989 Honda FourTrax 300, use a 10W-40 motorcycle oil that meets API SG/SH or higher, with Honda GN4 10W-40 as a reliable factory-recommended choice. Expect an approximate oil capacity of 1.8–2.0 quarts, including the oil filter. Perform regular oil changes according to the manual’s guidance, and use motorcycle-specific oil to protect the engine and transmission in this vintage ATV.
Conclusion
Maintaining proper oil type and level is essential for longevity in classic ATVs like the 1989 FourTrax 300. By sticking to a 10W-40 motorcycle oil that meets API SG/SH or higher and following the standard change interval, you’ll help keep this vintage Honda running smoothly for miles to come.
Related note
Always consult the original owner’s manual or a certified technician for your exact model year, as specifications can vary between production runs and regional releases. This article provides a practical guide, but the official manual is the definitive source for your ATV.
Sources and further reading
Honda service manuals, ATV maintenance guides, and reputable vehicle maintenance resources provide the exact oil grade, capacity, and service intervals for the TRX300. When in doubt, reference the manual or contact a Honda service center for clarification.
What oil does a 1989 Honda Fourtrax take?
3 quarts of OEM Honda GN4 10W-40 motor oil.
Can I use regular 10W30 in my ATV?
The engines are machined so that the chosen viscosity is most effective. In the example recommendation above, the manufacturer requires grade 10w30, so depending on the start temperature, 0W30, 5W30 or 10W30 would be good choices.
What type of oil goes in a Honda Fourtrax 300?
Synthetic 10W-40 Motor Oil
Valvoline 4-Stroke Motorcycle Full Synthetic 10W-40 Motor Oil 1 Quart. Products highlighted as 'Overall Pick' are: Rated 4+ stars.
How many quarts of oil does a Honda Fourtrax 300 hold?
2.4 quarts
NOTE: Honda specifies that the TRX300 engine takes 2.4 quarts of GN4 10W40 oil.