David,

The standard reply is that the water is best at around 190°F so the entrapped water will boil off at least. Running any modern detergent oil, and particularly a synthetic you shouldn't have a sluge problem. If you never hit 200 I might worry, but you should be fine. You could make the cowl opening smaller if you have nothing to do! A better fix may eventually be a smaller cooler, but to take advantage of the lower drag you will need a new smaller duct as well. Leave it alone for now. If you really worry get an oil thermostat bypass.

Sounds like you have plenty of inlet area, how many sq inches?

Bill Jepson