again, many marine engines never get drained from the bottom over thousands of hours of running in a much harsher environment than a car and are totally fine. My boat is a '84 with a SBC 350 that has 3000+ hours and has never been apart. Oil 100% changed through the dipstick, zero issues. Doesn't burn a drop, good oil pressure, runs like a top.
Even when you drain out the bottom you are contaminating the new oil, there is no way to get all the old oil out of the engine, nor would you want to.
Even when you drain out the bottom you are contaminating the new oil, there is no way to get all the old oil out of the engine, nor would you want to.


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