Changing the oil in a 2004 Honda CRF230F

The oil filler hole cap has an oil dipstick. Fill to mid range on the dipstick, about 2 quarts, just watch the dipstick. By the way, do not screw the dipstick in when checking oil level. Your bike does not have an oil filter. Use 10w40 motor oil in the gear box. Don't use any synthetic oils, oil marked "EC", or oil with "special" additives. Stick with the major brands; Pennzoil, Quaker State, Mobil or Shell.

The 2004 Honda CRF230F requires 1.1 US qt of SAE 10W40 engine oil. (In actuality, it may take a bit more than 1.1 qt.) I suggest to first add 1 qt and let it fully drain down into the crankcase (2-3 minutes). With the bike in an upright position and a clean dipstick, insert the dipstick into the filler hole - do not screw it in. Check the oil level. Add a small quantity of oil so not to overfill. (I like to have it at the top end of the range as apposed to "just enough".) Next, start the bike, let it run for 5 minutes, turn it off, let the bike sit for 2-3 minutes, and then re-check the oil level. Add accordingly to bring the level into the "full" range on the dipstick.

This bike does not have an oil filter. It does have an oil screen tube that is under spring tension and found when the side oil drain cap is removed. When the cap is removed, a bit of carb cleaner or contact cleaner (read the can to ensure it will not harm rubber components) can be used to remove deposits. (There is also a centrifugal filter that should be cleaned every 1,200 miles. This is a different topic.)

Regarding the type of oil to use: Synthetic oil is fine to use in the CRF230. If a synthetic is used, it does not mean that you can go twice as long (or longer) between oil changes. One of the biggest factors to engine longevity is changing the oil at manufacturer recommended intervals (every 600 miles for the CRF230 or annually, whichever is less). Use an oil rated at API Service Classification of SE or higher. Do not use non-detergent or "Energy Conserving" oils. IMO, you cannot go wrong with Pro Honda GN4 or HP4. (HP4 is Honda's synthetic WITHOUT molybdenum, aka "moly". Moly can cause operational issues in wet-clutch engines/transmissions, such as what the CRF230 has.)