Yamaha R25 engine oil specification

The specification in brief

The Yamaha YZF-R25 is specified for four-stroke motorcycle engine oil of SAE 10W-40 viscosity that meets API SG or higher and JASO MA (wet-clutch compatible). Yamaha’s own product for this fill is Yamalube 4 in 10W-40. That grade is the factory recommendation for the liquid-cooled 249 cc parallel-twin used in the R25 and the closely related MT-25. Exact fill volume, service interval and allowed viscosity alternatives are printed in the owner’s manual for the model year and market, and those pages take priority over any general figure.

Oil type, grade and approvals

Yamaha’s published requirement is a motorcycle-specific 4-stroke oil, not a passenger-car motor oil. The R25 uses a wet multi-plate clutch that shares the crankcase oil, so the lubricant must meet JASO T903 MA or MA2. Oils labelled JASO MB, and many car oils marked “energy conserving” or “resource conserving,” contain friction modifiers that can make the clutch slip. API SG is the documented minimum service classification; later categories such as SJ, SL, SM and SN are acceptable when they also carry a JASO MA or MA2 rating and a motorcycle application on the label.

Viscosity: SAE 10W-40 is the standard factory grade. API: SG or higher. JASO: MA or MA2 (wet clutch). Do not use JASO MB. Yamaha product: Yamalube 4, 10W-40, or an equivalent motorcycle oil meeting the same marks. Application: four-stroke, liquid-cooled, wet-sump parallel twin (YZF-R25 / MT-25 family).

Typical oil capacity

Factory service data for the R25 commonly lists three capacities. After any refill, oil level is set with the engine warm, the bike upright on level ground, and the sight glass (or dipstick, depending on year) as the final check. Overfilling can aerate the oil and raise crankcase pressure; underfilling starves the pump.

Service condition Typical volume; Periodic oil change, filter left in place about 1.80 L; Oil and oil-filter change about 2.10 L; Dry engine / overhaul total about 2.40 L

Those litre figures appear in multiple Yamaha R25 owner and service publications for the 249 cc CP2 engine. A later year, a different market manual, or a change of filter brand can move the actual refill by a small amount. If the glass sits below the lower mark after a documented fill, add in small steps rather than pouring the full dry-engine quantity into a used engine.

Viscosity versus climate

Yamaha viscosity charts for this engine treat 10W-40 as the all-round grade for the temperatures most R25 markets see. In sustained high ambient heat, some Yamaha charts also list 20W-40 or 20W-50. In cooler conditions, 10W-30 may appear as an option. Stay inside the chart in the manual that matches the bike; mixing grades in the crankcase is not a specified method. Fully synthetic 10W-40 motorcycle oils that still carry JASO MA or MA2 are widely used as equivalents to Yamalube 4, provided the API and JASO marks are on the bottle.

Service interval and first fill

Break-in oil is usually changed at the first inspection, commonly around 1,000 km, together with the filter. Thereafter many R25 schedules call for an oil change every 4,000 to 6,000 km or every six months, whichever comes first, with the filter replaced at the same time or on the interval the local manual states. Severe use (short trips, high load, dusty roads, track days) shortens that interval. Filter part numbers and torque for the drain bolt and filter are year-specific; use a new crush washer on the drain plug.

What this does not cover

This specification is for the Yamaha YZF-R25 249 cc twin. It does not automatically apply to the YZF-R3 (321 cc), the YZF-R15, or other Yamaha 250 singles. Fork oil, brake fluid and coolant are separate products with their own grades. No independent laboratory results or ownership test data are cited here; the figures above are the commonly published factory specification, qualified by model year and market. If the VIN, model code or owner’s manual disagrees with a generic 10W-40 / 1.8–2.1 L figure, follow the document that belongs to that motorcycle.

Practical next step

Buy a JASO MA or MA2 10W-40 motorcycle 4-stroke oil (Yamalube 4 or equivalent), plan on roughly 2.1 L if the filter is coming off, and set the level on the sight glass with the bike vertical and the engine warm. Confirm viscosity options, exact litres and the change interval in the owner’s manual for that R25’s year and market before the first purchase.