[markernineteen]

The gear lube in my lower unit is black and burned smelling . I change it twice a year and I'm using the best synthetic gear lube . There is no water or metal flakes in the drained oil . Is this normal for this lower unit ? I've never seen an outboard do this to gear lube . Everything works fine and the prop spins freely and smoothly by hand . This smell has me worried and it has happened with three brands of oil . Is trouble on the way ?

[robert graham]

if everything is as it should be, then the gear oil drained from your lower unit should look just about like new oil. sounds like you may have a bad seal/water in unit. remove your prop and check the seal. could also be drive shaft seal on top of foot which would require foot removal to inspect. if you run motor in salt water, then oil/water mixture in foot can get pretty nasty. Good Luck!

[hondon]

We're not there to see what you are seeing but it do'es not sound right.Centered around the driveshaft in the gearcase is a nylon wormgear that circulates oil from the bottom of the gearcase to the top and allows it to cool.If that gear has become spun on the flats of that shaft it will cause the gearoil to overheat and spoil very quickly.Not a common failure but not unheard of especially if that gearcase has been gone through and that nylon gear not replaced.

[JustJason]

use the mercruiser high performance (green stuff) in it and see if your problems return.