Can I lose oil through the oil cooler on a 454 mag efi? If so, would I notice my oil mixing with water? So far, I'm just using oil with no signs of water in my oil. I will use 1 quart of oil in 2 hrs of running at 3500 rpms. It seems that the starboard side exhaust leaves more residue on the transom and the inside of the exhaust tip. The motor runs strong other than the oil consumption. I changed the rings and bearings and had the cylinders honed about 40 hrs ago. I had oil consumption before the rebuild, but it didn't seem as bad as it is now. I believe I have being using this much oil since the rebuild? Any help would be appreciated. Thanks.

If you have breathers on your valve covers look for excessive smoke coming out of them, that is a sure sign of blow-by. Compression check to make sure your rings are doing their job properly.

If your using synthetic you will consume some normally.

I would run a cylinder leak down check. It will take all the guess work out of this problem.

Yes you can leak oil out of an engine oil cooler into the water system. Remember the oil system running has far more pressure 50-60lbs than the water system and you will never see the loss. I should pressure check your oil cooler to make sure its ok. Sometimes guys forget to change the zinc plugs in the cooler and the cooler passages can corrode thru. Just a thought.
Raylar