I had the same problem, it is condensation. Key evidence is that the oil is ok when you check it.

Install a pcv valve system and your problem will evaporate in a trip or two. For now, leave the fill caps and breathers off during the week layup to let evaporation work its magic inside the engine. Also, if you made any idle adjustments to the carbs (lowered it) turn it back up to make sure this is not reversion. I would guess that is the cause myself, but pcv should do the erradicate the issue. At least it has for me in the past.

BT

Mark, Correct. And the HP 450s didn't have them, if memory serves me, because we had a handful of problems exactly like this with those motors.

Many things can lead to moisture in your oil. Gasket, headers,poor exhaust valves and temps. Typically condensation will form on the top of you valve covers and intakes. It typically happens more often in areas were the outside temps are cooler. Next time you run the boat get the motors up to operating temp for a period of time and see if the moisture starts to burn off. If your oil temp doesn't reach boiling point it will not remove much condensation. Most open breather motors will make condensation so I wouldn't worry to much about it. If it really bothers you K.E products offers an in-line thermostat that works well.

Whatever you decide to do, run an oil filter like mobile 1 so it doesn't clog with moisture from the oil. Lose the fram they are crap.

OMG!!! Condensation......In the valve covers!!!!!! I think you should sell the whole thing to me!!!! I could use 7 more feet!!! Especially if it's an AT!!!!!!!

I did change the oil and filters ran it for over 20 minutes and oil got up to temp so did water shut it down checked the oil on the dip sticks they both looked like brand new not one drop of water. I'll change this oil now and put the mobil 1 m1-302 filters and new oil it again just to make sure.

Hey I just might sell it we want to go alittle bigger say a 38

You canīt really check the oil on the dip stick since the oil in the dipsticktube stays in the tube ! Unscrew the filter and check it there that will show you what the oil is like.

Cigaretteman

During my milkshake adventures the oil on the dipstick always looked fine. I got used to cracking the filter to let some seap out so I could check it there. Cigman is right on.

BT

The above are correct, there is no oil circulation in the dip stick tube