Roger Long wrote:
If you have sufficient bilge below your engine, is there any reason
you can't use an outboard fuel line squeeze bulb in a hose to siphon
the oil out?


Strictly speaking, a syphon uses gravity to pull a liquid to a lower
level. Your idea would use the primer fuel bulb pump to move the
oil. The valves in the bulb slow down any syphon passing through it,
some worse than others. Molasses and thick oil both move very slowly
unless urged well.

The oil is thinner when hot, but likely would not move quickly
enough to satisfy you. You would get a cramp in your hand, I fear,
before you moved much oil That way, as the bulb does not suck very well.

I use a small barrel type pump to suck the oil out the filler neck,
it's slow enough, and messy, but works. A permanently plumbed hard
line from the oil pan drain and a good small pump, or a downhill
drain, if there is depth enough to your bilge, will do the job
conveniently, especially if you warm the engine oil before draining.

There is a type of pump that establishes a partial vacuum in a
collector vessel, specially designed for oil changes that I hear is
more satisfactory. You may find it at auto supply houses, if you look.

Terry K