The 1998 Honda FourTrax 300 requires SAE 10W-40 engine oil that meets API service category SG or newer, and it holds about 2 quarts (roughly 1.9 liters) with a filter change. A common and reliable choice is Honda GN4 10W-40, but any reputable 4-stroke motorcycle oil meeting the same API spec is suitable. The engine oil also lubricates the transmission, so no separate gear oil is needed for the final drive on this model.
For context, the FourTrax 300 is a four-stroke ATV where the engine oil serves multiple moving parts, including the clutch. When changing oil, replace the filter as well and refill to the correct level. Always consult the specific owner's or service manual for your sub-model (TRX300FM, TRX300FW, etc.) and your climate, since capacities and recommendations can vary slightly.
Oil type and grade
Below are the core oil specifications you should consider for this model. The list covers the recommended grade, compatibility, and options.
- Engine oil grade: SAE 10W-40 (API SG/SH/SJ/SN compatible) – Honda's GN4 10W-40 is a commonly recommended option.
- Oil compatibility: Use a reputable 4-stroke motorcycle or ATV oil that meets the API service category noted above; conventional or synthetic blends are acceptable.
- Transmission relation: No separate transmission gear oil is required; the engine oil lubricates the clutch and gearbox inside the crankcase.
- Oil change practice: Change the engine oil and the oil filter together at the same time for best results.
In short, choose a 10W-40 oil that meets API SG or newer, with Honda GN4 10W-40 as a solid standard option, and ensure you replace the filter during the oil change.
Notes on modern oils
If you ride in extreme temperatures or prefer synthetic blends, you can opt for a 10W-40 synthetic or synthetic-blend oil that still meets the API SG or newer standard. Avoid oils that do not meet the required API specification or that are outside the recommended viscosity range for this model.
Capacity and service notes
Before the list: The following figures and steps summarize capacity and maintenance guidelines for the 1998 FourTrax 300. Exact numbers can vary slightly by sub-model and whether the filter is replaced.
- Oil capacity with filter change: about 1.9–2.0 quarts (1.8–1.9 L).
- Oil capacity without filter change: typically around 1.7–1.8 quarts.
- Service steps: Warm the engine, drain old oil from the crankcase, replace the oil filter, refill slowly to the correct level, run briefly to check for leaks, then re-check the oil level.
Following these steps ensures proper lubrication of the engine and transmission, with the filter change helping to maintain oil quality over time.
Additional maintenance tips
To keep your FourTrax 300 running smoothly, consider these tips: check oil level regularly, especially after long rides or heavy use; use oil that meets the API specification; replace the oil filter with every oil change; and consult the owner’s manual for exact capacity and service intervals for your sub-model and climate.
Summary
The 1998 Honda FourTrax 300 takes SAE 10W-40 engine oil that meets API SG or newer standards, with an overall capacity near 2 quarts when changing the oil and filter. The engine oil also lubricates the transmission, so no separate gear oil is necessary for the final drive on this model. Honda GN4 10W-40 is a dependable, commonly recommended option; always verify exact specifications for your sub-model in the owner or service manual.