Well i have a 1990 Four winns 190 freedom with a 4.3 engine. While i was checking the oil today after a LONG day at the lake sunday I checked the oil and noticed it was full and color was good (No water in oil) BUT when i took off the oil cap to see how clean the engine was inside i see rust depostis inside the head on the springs and on the Cylinder head casting (It looks fresh) I being in the automotive field am VERY good at maintaining my vehicles.Boat and i want to know if i need to worry now and get it into the shop Again or is there a Oil that i can use to get rid of the rust deposits in the engine. I have noticed a little hesitation minor vibration but nothing major. The boat was given a clean bill of health from a local Recognizable shop here in phx az. So i am wondering if i need to start saving up for a major repair (Another 1800.00) or what? the 1800 was for a complete tune up and all fluid change and some other garbage. Please let me know what i should do any ideas, Like i say the rust is on the inside of the head and there is NO WATER UNDER OIL CAP! so i think im clear of a head gasket failure. Thank you dave