In 1986, Honda released a new line of ATVs -- the FourTrax -- and in its debut year, the FourTrax came in two models: the high-performance TRX250R and Honda's first full-time four-wheel-drive ATV, the TRX350. The 1999 model year brought the introduction of Honda's new TRX400EX high-performance quad, following a hiatus from high-performance quad building that lasted more than 10 years.
Oil Type and Capacity
The 1999 Honda 400EX holds a total of 2.3 quarts of oil. When you check the oil via the dipstick, the oil level should be between the "Upper" and "Lower" marks. Honda recommended using 10W-40 engine oil with API Service Classification SF or SG.