HPDI Lower Unit Fluid

[Thamelau]

I have a weird question. Every time I change my lower unit fluid, it doesn't seem like 1 quart comes out, but it always takes about a quart to fill. It is never milky, there is no water that comes out separate from the oil, and nothing else that I notice being noteworthy. Is it possible to have a leak that lets fluid out, but not water in? I never have a spot on my garage floor from a leak either. Maybe it is a quart coming out and just doesn't seem like it.

Also, my dad changed the fluid and asked if GL5 was good in my motor. I have read somewhere that I should be using GL4 because GL5 can corrode brass/bronze and the HPDI uses brass/bronze bushings instead of bearings. Anyone worried about this?

[21XDC]

Mine is always low as well. Filled full when changed. I use Amsoil universal marine gear oil.

[Amistad Tackle]

Yamaha lowers lose lower unit lube. The way the two seals on the prop shaft are oriented (one with the lip in and one lip out) are good at keeping water out but lube is lost when running. That is how it was explained to me. You should check and top off the lower unit lube at least a couple times a season. Change it every 75-100 hours. Use new washers each time. A new OEM lower for that engine is $4,500. Checking, and toping it off is cheap insurance.

I had fishing line behind my thrust washer. Could not see it. Ran until it was too late and had some lower noise. Most of the lube was gone. New lower was required.

[Thamelau]

Thanks guys, I am not crazy. I'll start checking it and topping it off through the season.