Yesterday was oil change day, so I did my normal routine of warming up the generator and it ran just fine. Used the oil pump and pumped out a gallon of oil and changed the oil filter, pumped a gallon of new oil back in and changed the racor fuel filter. I went to start the generator after prime and preheat and it would not turn over just one Klunk like it wanted to turn over, thinking it just needed to be primed more I tried this several times but just one klunk. Then I noticed lots of oil in the pan under the generator, pulled the dipstick and oil poured out of it. Thinking no way did I put too much oil in, I started pumping some of the oil out, it looked funny, I believe that coolant somehow mixed with the oil. Ugggg! How is the oil leaking out the bottom, cracked block? Oil filter was tight, no sign of leaking.