Hi, I recently purchased my Mazda and have had it for about a month and went to check the oil and it was extremely low so I went ahead and changed it instead of adding any. I put Mobil1 full synthetic 5w30 in it and then went on a road trip which was about 150 miles total. When I returned home I went to check the oil and its at the bottom of the dipstick again. I checked for leaks and the exhaust and no smoke other than it being could. Does anyone know what this could be? I also checked the spark plugs and they were bad so I changed them and in the process I looked in the spark plug hole and seen black muck sitting on top of the pistons. Thanks for any help.