I took the boat out yesterday to find both flame arrestors and breathers were caked full of that milky white stuff the motors seem to run perfect though. The compression on one motor idle is a 2 or 5 pounds of pressure after running for a long time after I put it up on plane it goes up. I just looked at the oil on both dipsticks and the oil looks perfect. I also just changed the oil and filters in the boat before the run I put the new mobil 1 15w-50 and mercury racing filters. The motors are 1996 450hp's mercs. Please anybody call me if you have any ideas or post them I hope I didn't nuke both motors!!!!
Jason 1-608-449-4992

Since the oil on your dipsticks is NOT milkshaked you should be in great shape. What you are seeing is condensate. You probably should install a vented breather cap system to eliminate the condensate build up.

I have a vent breather on every valve cover it was worse than the picture shows believe me!! This is a picture when i run my finger on the inside of the valve cover

Sorry wrong picture this is it!!!!!!

Need To Get The Oil Hotter , To Big Of A Cooler Will Cause That.but It Should Not Cause That Big Of A Problem.

do you run a thermostat or crossover?

Thermostat it calls for a 143 and thats whats in them. I was running between 140 and 150 oil coolers at 200 to 230 This problem only started a week ago and thats when I tried that new 15w-50 mobil one

Oil thermostat keeps the oil at 200-230 degrees. Burns off the condesation above 212 degrees.

Pulled all four breathers off and cleaned them they were plum full of that goop. What is so weird to me is that it's both motors at the same time doing the same thing!!! Also drained oil and replace with just 20w-50 oil and cheap fram filter and runs fine oil pressure is better than mobil 1 no water on dipsticks still goop from valve covers and breathers!!! What do you guys think????

might have taken in some water through your pipes... same thing happened to me last week... flushed it out and its fine now... stecz