I have a 2004 Merc XR6. The motor performs perfectly with one small but annoying glitch. The remote oil reservoir up on the engine is constantly about an inch low. This causes the float to bounce with the waves and create a intermittent beeping(alarm). Not the "normal" beep-beep-beep that signals low oil level, just beep-wait till the next wave- beep etc. The float, at its lowest point, makes a contact the produces the beep alarm. I have run the engine (several times) with the oil cap off until the level rises (overflows), but that only solves the problem for a day or two. Mind you, the oil level never goes more than an inch or so low and the is just enough for the float to signal the loss of oil which, if the loss progressed, would allow for a half hour or so of running before depleting the entire remote supply and possibly damaging the engine. I have removed the cowl dozens of times to check the oil level and have never seen it run lower than the aforementioned inch or so after several days of operation. I'm tempted to simply disconnect the wires to the float alarm to stop the incessant and, seemingly unnecessary, beeping.

It's like the old fable about the boy who cried wolf (for you older folks.)

Any similar experiences and/or solutions to this minor, but aggravating, situation? Thanx in advance.

I had an issue like that with an Optimax. It took a new upper tank to fix it.

I had the same motor. Sometimes the upper tank would develop a small crack around the neck area with age and that would happen. I had to change the tank.

It is my understanding that, for the oiling system to work properly, it has to be air-tight. The oil pump must create a negative pressure to draw oil from the main 3 gallon tank, past the one-way valve on the engine and into the reserve tank mounted on the engine. Any "leak" in the system will cause a loss in negative pressure and the oil will drain back into the main tank. As I said before, I have primed the system many times by removing the cap and running the engine at idle until the oil level rises and overflows. Having the cap removed creates a much greater "leak" in the system than a "small crack" as described. The fact that the oil pump is able to draw oil up to and overflow the reserve tank proves that the system is able to provide lubrication to the engine. When the cap is replaced the oil level will drop no more than an inch or so which is just enough to cause the intermittent beep alarm that I'm trying to eliminate. Any crack or leak in the system will prevent it from maintaining any oil level at all and will result in serious damage to the engine as it becomes starved for lubrication.

Has to be another explanation.

There’s no doubt, you are losing pressure in your oiling system. You just have to find where. My old 929 NITRO with a 225efi did the same thing. We chased the problem for a long time and like you, I was refilling the saddle tank with the engine running as specified by Mercury. I sat with my merc mechanic and we went over all the possibilities. Starting with saddle tank. Bad cap (known failure item), bad sensor, bad tank, bad line from bilge tank to saddle tank, bad cap on bilge tank, bad bilge tank and finally bad oil pump (my efi had a switch to fill saddle tank as well). It ended up being a hairline crack in the saddle tank. Enough to let it lose pressure but not big enough to leak.