Lower Unit Gear Oil

[pmergler]

'65 33 hp 'Rude. I tried to replace my lower unit oil the other day and was unsuccessful. I have a couple newbie questions, sorry first time changing lower unit oil on a boat. I did get new screws and washers for the change. First question, is there a difference between lower unit "lube" and lower unit "oil"? Which should I be using? I bought some Pennzoil Marine Lower Unit gear oil High-Viscosity W80/90, I am assuming this is the right oil. When I drained the existing lower unit oil it was dark green and much thicker then the new stuff (I assume it is just old).

Next I tried to refill the unit by putting oil in from the bottom drain screw, but now matter how hard I squeezed the bottle none of the oil would go into the lower unit. I just don't know if I wasn't squeezing hard enough or if I should go get an oil pump. So how hard to you have to squeeze and for how long to fill it?

Again sorry for the "very" newbie questions.

Thanks in advance,
patrick

 

[rickdb1boat]

Re: Lower Unit Gear Oil

Did you remove the vent screw? You will have a drain screw and a vent screw. Both slotted type. Don't remove the one with a phillips head. It normally goes in pretty easy when you squeeze the bottle...Mine fills up in about 30 seconds squeezing the bottle firmly...

 

[Paul Moir]

Re: Lower Unit Gear Oil


Lower unit lube = lower unit oil. Some really old outboards used a thin grease so "lube" (lubricant) is the generic term that covers both.

That's the right oil. Hi Vis 90 weight, without a W rating below about 80. Lower unit lube will get very thick if it's very old, don't ask me why. Also if the old lower unit lube is straight 90 weight the multi-viscosity lube (80w90) will appear thinner.

Should take on just shy of 14 oz.

 

[jtexas]

Re: Lower Unit Gear Oil

They make a pump, for about $7 at walmart or basspro or academy, that fits right into a quart bottle of lube, and screws into the plug hole.

Pump until it starts coming out the top vent hole...screw in the vent screw, unscrew the pump, screw in the plug, and hit the lake!

Then empty what's left of your squeeze tube into the quart bottle for next time.

Old oil dark, thick is okay...means no water intrusion...little bit of metal filings on the plug magnet ok, chunks or splinters indicates a problem.

 

[pmergler]

Re: Lower Unit Gear Oil

Cool thanks all

 

[fireman57]

Re: Lower Unit Gear Oil

Had same problem of oil not going in. Spin the prop a little by hand and it will go in easily.

 

[GlasV162]

Re: Lower Unit Gear Oil

One other pointer..............there should be a nylon seal on your drain and fill plugs. Not a bad idea to replace them while you're at it.