Lower Unit Oil Change
Routine checks and maintenance of the lower unit is vital for proper operation and dependability. Lower units will fail quickly if its low on oil or if contaminated with water. The most common reason a lower unit fails is due to water contamination.
NOTE: Never attempt to service your Honda Outboard without the use of a repair manual.
Water present in the lower unit is most often a result of fishing line or other materials entangled in the propeller shaft, which damages the seal. If these materials go unchecked, they will cut through the seal allowing oil to escape and water to under. Fishing line gone unchecked over time can actually cut through the propeller shaft. Always inspect this area often.
The following lower unit oil change procedures are for Honda outboard motors. Its recommended to always use a repair manual when attempting to service your outboard engine. Critical data, additional precautions and step-by-step procedures are included within the manual.
Honda Outboard Years This Applies To:
1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001
Honda Outboard HP Ratings This Applies To:
2HP 5HP 7.5HP 8HP 9.9HP 15HP 20HP 25HP 30HP 50HP 40HP 45HP 50HP 75HP 80HP 90HP 100HP 115HP 130HP
Honda Outboard Models This Applies to:
BF15A BF9.9A BF50A BF5A BF20 BF2A BF15 BF25 BF100 BF80 BF50 BF75 BF50 BF8A BF40A BF30A BF25ABF15A BF45A BF35A BF25A BF130A BF115A BF90A BF75A BF
Oil Changing Procedures
1. Position a container underneath the lower unit.
2. Un-tighten the oil level plug using a flat head screwdriver. If the plug cant be removed, the lubricant service cant be performed.
WARNING: Never attempt to remove the vent or filler plugs while the lower unit oil/lubricant is hot. The lubricant expands when hot. Removing the plug while the oil is hot will cause the lubricant to jet out and cause serious burns.
3. Extract the fill plug from the bottom of the gear housing, the remove the oil level plug.
4. Wait until all the oil has fully drained from the lower unit.
NOTE: Inspect the magnet at the end of the drain screw (if equipped) for metal particles. Some metal particles is a sing of normal wear, however, if metal chips or excessive particles are present, disassemble the gear case for a closer inspection.
5. When the used lubricant drains, check for the presence of water (seen as a white milky substance), and for the presence of metal particles. If any of these condition are present, service the lower unit immediately.
6. Position the lower unit in a vertical position, without allowing the outboard to list to either side. It must be positioned in this manner to properly fill the lower unit.
7. Position the lubricant oil fill tube into the oil drain hole located at the bottom of the lower unit. Then begin to inject the lubricant until excess lubricant starts to come out the oil level hole.
8. Reinstall the oil level and vent plugs using new washers or gaskets, then install the oil fill plug.
9. Dispose of the use lubricant at an authorized lubricant recycling station.