First day out this year and the port engine oil temp is running around 140. Maybe 150 deg. at 4500 RPMs and the starboard engine hits 140 creeps to 150 than 160 than once on plane 200 degrees and continues to rise. Went to 220/225 and I backed it down. Tried three time with the same results. All other readings (water temp, pressure, water flow, etc. etc. are perfect. I didn't want to hurt anything with one engine temp in the 140s and the other over 200. Any thoughts?

220 225 isn't that bad .although oil temp of 140 id be worried about . need to get to boiling point to clense the oil of water ,condensation

Anything over 212 (boiling point of water) is good to get rid of condensation. Both mine run 220 cruising and 250-255 running hard.

Lol.. Didn't mean to say basically the same thing, didn't see your post.

250* Would worry me. Mine run 180 cruising and 210 wot .

I thought the same for the last 3 years but everything has been fine, and oil looks good when changed. Back flushed the coolers and system last year. Water temp never moves off 140. Hope I haven't been hurting anything at those oil temps!?

With a good synthetic you're prob ok. I would be scared to continually run dino oil at 250*. I believe on the Merc 525, 220 or 230* oil temp the alarm comes on. On my semi trucks, engine goes into shutdown mode at 240ish I believe. Most new cars and trucks with oil temp gauges, stay fairly consistant with coolant temp, around 200-220. Canton racing, and all the other companies who make oil stats, pretty much design them around a 180-210* temp.

I have the Merc racing filter heads with internal oil thermostats. Ive tested these thermostat elements in boiling water. The begin to open around 180*, and full open at about 200-210. Which is pretty much what I see on the gauge. My 10qt pans, 65* lake water, and no water stats, pretty much bypass the oil cooler until I start romping on it. With a supercharged marine engine, I'd rather keep the oil on the cooler side. Helps keep those valve springs cooler, a bit more viscous for metal/metal, etc. Plus running no water stats keeping the block and heads cool, helps ward off the evil detonation. Im no engine builder or oil expert, so take my thoughts with a grain of salt.

I have 10qt pans also. I run amsoil 15-45. Not sure if I have oil thermostats or do most have them? Have to check that out tomorrow.

Most setups don't have oil stats. Merc used them on the racing blue motors, and aftermarket co's like hardin marine, Teague, etc, sell them. What size coolers do you have? I'd try removing the 140* water stats, and see if the oil temp comes down 40-50* at wot. Even here where the water's cold, us blower motor guys don't run water stats.

Not sure on the cooler size. I have heard of guys drilling holes in them but never thought of removing them all together. Isn't some heat better than running cold? Idk.