What type and quantity gear oil for 1998 Honda foreman 400?

For a 1998 Honda Foreman 400, you should use SAE 10W-40 engine oil for the engine and Honda's GN4 10W-40 or an equivalent high-quality motorcycle oil. The gear oil for the transmission and final drive is typically Honda Pro GN4 10W-40 or an equivalent high-performance gear oil. The quantity needed is approximately 2.5 quarts for the engine and about 0.9 quarts for the transmission. Always check your owner's manual for specific recommendations and maintenance intervals.