I ran generic TCW3 in college when I had no monies. My friend and I were both having issues with water ingestion. He switched to Mercury Quicksilver and his problems went away. I had always noticed a light blue frothyness on my plugs when I ingested water, so I did a test.
I mixed oil 10:1 with water in 2 clear cups of equal sizes with equal amounts of oil in water in each. One had Generic TCW3, the other had Mercury Quicksilver. I shook the bottles vigorously and let them sit. The Mercury Quicksilver immediately began separating like cooking oil, it beaded and floated. The generic oil turned into a frothy mess, it did not bead up, and all of the water had a light blue tint to it.
I run quicksilver over other oils because the Mercury Dealer local buys it in 55ga drums and sells it by the gallon, so it's $21/ga for me (opposed to $28/ga at walmart, $30+ at westmarine). Quicksilver is a premium oil, but I buy it over the others because of the discounted price. At $30/ga, there are a lot of options.
I'm not sold on fully synthetic oils at $35 / 0.5ga ($70/ga). I have a stock motor, and I know from my friends that had limited blasters and my limited X2, no harm has come from running quick silver. I'm sure if you have a $30,000 boat with a $10,000 motor, $70 of oil is a great price. I run a few hundred gallons of fuel through my ski each year, so the amount of money saved over buying unnecessary oils is in the hundreds.
In any case, at the minimum, do the same test I did. If your oil doesn't immediately separate from the water, change to a better oil.
