ya that's probably it. And replace the fuel filter too right? :D
If you were serious, sorry.
Hey I'm not ruling anything out just yet though.

Why take the cahnce of messing something up, take it back to the dealer. It has to still be under warranty if it is an 08. Just my 2 cents

It's caused by the oil in the pan being high to the point that it rises above the windage tray or if no windage tray, either way the crank whips the oil, aerating it and literally making it froth and/or foam. I know this because it's happened to me with inferior aftermarket oil pans that advertise capacities that are two quarts larger than they actually hold. Did I say Milodon????

I wasn't kidding. It happen to me last year. I could not figure out what it was so i called mercury racing and they told me it was the filter. I changed it and thats what it was. If anything goes wrong inside the filter than the oil will bypass the filter and dump the un filtered oil back into the pan. The pressure will stay between 20-25#. It scared the chit out of me when it happen. I was running about 80 when the pressure dropped. The oil temp will climb also because your than by passing the oil cooler. Its only 10 bucks. Change the filter first to see if that helps.

Got it. Thanks!

Are you getting a hard alarm and going into guardian mode? If your not your probly fine. The Smartcraft system has its own sensor that supplies info to the ECU. Your guage runs off the traditional sending unit off the back left corner of the motor on the oil gally.
I wouldn't mess with trying to hook up a mechanical gauge. Find someone with the merc scan tool or Diacom. Hook it up and go for a ride while it is recording. It will give you the actual oil pressure off the computer. My guage reads lower than what the computer does.

No alarms and no guardian mode. No change in performance at all when this happens. The pressure just slowly drops off from 40psi while getting on plane and as the rpms go up. Then it just flutters between 20 and 25. I thought the same thing about trying to hook up a scan tool but I don't know anyone than has one. I'd actually buy one if I could find one cheap enough. I'm sure it would come in handy to have one.

I drained about a qt out tonight and plan to get it in the water no later than the w/e. I'll check the oil level at rest in the water and make sure I'm in the range but not even close to over before I fire it up and run it. If it still happens I think I'll replace the filter and throw in new Merc synth blend and try it again. Again making darn sure I'm not over. If it still does it then I'll be forced to add a mechanical gauge just to make sure it's not a gauge or sending unit problem. A scan tool would make this much easier thats for sure.
Hopefully I'll have some answers soon and it will just be operator error. I could handle that even after 30+ years of boating. :)
I know it's under warranty and nothing against the dealers but I just hate to take my boats to the shop unless I absolutely have to. Especially a brand new one like this.
Thanks for input!

Any possibility that water is getting in the oil?
A "milkshake" in the top portion of the engine will also make a froth and cause the oil pressure to behave just as you indicated. You might check under the oil filler cap to see of any indication of this.

Closed cooling. Would have oil in the surge tank before coolant in oil.

No signs of any moisture but I'll double check.
Thanks