the main reason for petrol in your oil is the piston rings worn, which means the petrol is running down the side of the piston into the sump where your oil is retained, worn piston rings will give you a severe loss of power,replacing piston rings is a major job and cost major money, you would be cheaper getting another engine,petrol in the oil thins it down so it doesnt do its job properly so only makes things worse, hope this helps, good luck.
michael k
March 2012