What is the fitting in the bottom of the bottle?

The fitting should be the low drive oil sensor. I know this first hand. I got a case of tinkeritis this winter and decided to clean the bottle out. I broke the wires off of the sensor in the process. I too was offended when they told me 80 bucks for a plastic bottle and sensor. What a rip off. Anyway, while we are on this subject, my drive oil in the resivoir usually drops about an 1/8 to 1/4 of an inch in a weekend. Anyone want to take a stab at why? The drive oil was changed this winter and they didnt get the o ring seated right. That drained the bottle but once that was fixed the level held steady all winter. I used a little oil the first trip out but wrote that one off to air bubbles. But each time out after that I have used some. Albeit very little but some. The drive was pressure tested in a tank and no bubbles were present and the pressure guage didnt move. I think they had it under pressure for an hour or so. I notice no oil sheen on the water and no oil in the bilge. The outdrive has no oil running down the sides or out of the propshaft seal. Im puzzled. It has to be going somewhere. One thought though. I have been pulling the oil drain plug to check for water about every other trip. There hasnt been any in there. Could I be letting air in the drive and that is why the level in the bottle drops a bit?

I would put the pinhole in unless the top does not fit tight. It needs to be able to move air out and in as it expands and contracts.

I believe the Bravo seals are designed to leak just a little to lubricate themselves.

I have a Bravo I that is always low too. I thought it was the reservoir so I cleaned and resealed it last year. It continued to leak so I replaced the hose and clamps. Everything looked good until the last few months and I am low again.

I had the unit pressure tested, never have had water in the oil, and had decided to just live with it. I was also told that Bravo seals allow oil to leak out one way but not let water in.