Greetings,<br />I need to know if this is overkill. I have a 1999 merc 3.0 with Alpha 1 I/O.<br />Typically on my car engines about every 5 years I flush the radiator and block with a purchased cleaner and change the antifreeze.<br /><br />So, is it over kill or can I harm any parts if I put the outdrive in a tube, use some block cleaner, run the engine for a while, rinse and replace the block cleaner fluid with fresh water using the muffs, and then instead of draining the water, fill the tub with some antifreeze - run the engine to circulate the antifreeze and then leave the block filled with antifreeze instead of draining the water. Your thoughts please.<br />Marty