Based on my research, all engine models used in 2000 Cavaliers take 4.0 quarts. Since oil expands when hot, I put in 3.5 quarts. I check the dipstick after the next time I drive it enough to fully heat the engine (usually about 15 minutes). To check the oil level, park the car on a level surface and turn the car off. After removing the dipstick, wipe it off, re-insert, then remove again to check the oil level. Add more oil if needed.