Re: Chaging Gear Oil On A Force 70HP Outboard
1 is fill, 2 is vent. (or possibly the other way--it should be marked on the leg) 3 is drain. Do not touch 4. It is the pivot pin for the shift yoke and should NEVER be removed except when disassembling the lower unit.
To change the oil open 1,2, and 3 with the engine vertical let all the oil drain. close 3. fill through 1 until oil comes out 2. let stand for about 1/2 hour to let any air rise and top off through 1 until oil again flows out 2. Tighten all plugs firmly.
Best to use marine grade lower unit oil. It comes in various weights AND also synthetic. Choose whether you want the expensive brand or generic Wal Mart Super Tech. Auto rear end hypoid oil is acceptable, but marine grade has more emulsifiers and corrosion inhibitors.