Re: Should the lower unit be flushed before new lube is added?
Generally i just drain it and i wait awhile to make sure that most of it comes out (while the motor is level to the ground not tilted) i check it for water contamination and metal shavings or pieces if you have either of these symptoms the lower unit needs service. You can buy the gear oil at autozone they sell it in little yellow and white tubes i believe. There are two types of oil though you dont mention what type of marine engine you have but if its an old electric shift unit you have to use special gear oil "Type C" autozone usually carries that too.
