Well there super fine and hard to photo. But I got the oil filter cut open and it is littered with brass dust, and 2 small metal slivers. My guess is : Spun a bearing perfect!, is spun a little and plugged the oiling hole, and that is why I still have oil pressure.

Here are the filter photos. Best I could do. Whats your guess? Free beer in my garage to the winner once the motor is pulled :-)

http://i212.photobucket.com/albums/c...psvawebxvj.jpg

http://i212.photobucket.com/albums/c...ps7sdjbdyp.jpg

http://i212.photobucket.com/albums/c...pse993igc2.jpg

http://i212.photobucket.com/albums/c...psq4ntyegc.jpg

If your wondering I run Mercruiser oil filter PN: 35-86634K01

Made my guess a while ago. Spun and hammered main.

I know your pain. Saturday lost rpm, and oil pressure shut it down as soon as was safe. Idled back to ramp on other motor and pulled boat. Just came in from the garage from cutting oil filter apart and dumping oil out of it. My oil is nice and shimmery just like a stripers chest lol but not really funny. The filter is sparkley just like yours too. The oil on the dipstick had small chunks in it and smells burnt. So much for my supposed newly rebuilt motors. I have less than 4 hours on them and probably 2 of the hours on each motor is at slightly above idle after coming back on one motor twice, each time was a different motor and now this. I have yet to come back to ramp with both motors running correctly.

What causes a spun main?

Nice breakdown from clevite here, with pics to compare for the teardown:
http://www.wilmink.nl/Clevite/Clevit..._tech_info.pdf

So, you'll have to examine on teardown to know, but oil starvation, inadequate crush, and incorrect assembly are the top 3 IME.

Normally too tight clearance, bad or no line bore, out of round caps/bore, lack of oil, contamination of oil from other things going bad (rare) because if filter.

If you have loose clearances and not enough oil pressure will cause it also, but you said you had 70psi so that should not be the case for you. I would address line bore for sure.

This also I would like to know ill read threw apollard's link. Well I know there was plenty of oil in the forum of 8 qts. Incorrect assy after 20 years this engine has been in service, ruling that out also.

Ill scan the computer before I pull the engine to get the hrs.

Only thing I did different was changing to marine syn-blend oil, (from conventional ), and replacing 1 qt with Lucas oil Heavy Duty Oil Stabilizer. (we call it snot). Can this cause it?

What kinda oil filters? You cannot run normal filters that have built in bypass in a boat gotta be non bypass fikter because if the coolers the extra pressure allows unfiltered oil to go past

Ah forget it.