My kia is not starting what could it be on 1999 Kia Sportage

Me and my dad changed the belts the heater core the head gasket and the computer but there is still water getting in the oil what could it be

Asked by for the 1999 Kia Sportage
Is it water or 'bad gas' that's getting into the oil? Question is all over the place???
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Don't know why you had to change all the parts you mentioned but....If the gasket was done properly then the engine block itself may be cracked. Need to have inspection done to see if this engine is still serviceable.
Well it use to be my grad fathers it's been sitting for 3 years could it be because of the bad gas