4.5 qts using the sort of small Merc OEM oil filter is the oil capacity for these and the 5.0 and 5.7 cat engines.

IN THE WATER - Merc procedure is run engine until warmed up then shut down and allow min of 5 mins for oil to drain back down in oil pan. Pull dipstick wipe clean the reinsert and wait one minute then pull dipstick again, Your oil level.

the oil must be within the OK range and above the add mark. OEM factory procedure to a T and even in their Service Manual # 51 for the 6.2 CAT engine.

thanks for the help. I looked through the manual and see that point of checking while in the water.

Last question out of curiosity. Does the oil drain out of the filter when the engine is at rest? When I took my filter off, it was all but emply(I slightly unscrewed the filter from it's base). No oil leaked out, but when I completely removed the filter, it was empty...for the most part. I am wondering if the capacity is increased when you add a larger filter, or if it doesn't matter as all the oil just drains back anyway.

That all depends on the filter.
Some have anti-drain back valves.
Some don't.

I prefer the Wix Racing filters which are sold at Napa under their brand, and they do have said valve getting your motor oil faster at start up.

You should always use a filter with the anti-drain back valve on engines with an inverted remote oil filter pad. Like Brian, I use Wix (Napa Gold) which I know have the valve. Once you break the seal on the filter and let it sit awhile the oil will drain out of the filter back down the remote filter base. It is amazing to me the lack of oil capacity and coolers on the newer Merc small blocks. A few years back a bunch of us were running hard from Ha Ha Tonka back to 4 Corners at LOTO. We came off plane and a buddy of mine with the 6.2L MPI was yelling at me that he had no oil pressure. Engine was perfectly full of Merc 25W40. Pressure slowly climbed back up after a bit of idle time. Scared the crap out of him. I got him to change over to the larger capacity filters and Mobil 1 15W50 after that episode.