do i have a cracked head or head gasket

A cracked head or blown head gasket normally allows water to mix with the oil, overheating and coolant loss. Oil in the exhaust pipe and oil in the air filter housing is usually engine wear, (usually worn engine bore pistons or piston rings). A cylinder leakage and compression test are good tests to access engine wear. A "Block Check" is a valid test to test the cooling system for a blown head gasket. The most accurate way to test for a blown head gasket on a gasoline engine is to test for the presence of carbon monoxide in the cooling system. Snap-On, Matco (part # CO 2000), and Napa sell a tool to check to carry out this test. Another link to a supplier of this tool is http://www.etoolcart.com/combustion-leak-detector-lis75500.aspx. Carbon Monoxide is only present if there is a blown head gasket or cracked cylinder head. http://www.arrowheadradiator.com/head_gasket_or_combustion_leak_test.htm I think the napa part number 700-1006. http://www.blockchek.com/instructions.htm . Signs of a blown head gasket are coolant loss (frequently have to top up the coolant level of the engine without seeing an obvious leak), experiencing over heating or rough engine running or the presence of white sweet smelling steam from the exhaust. A badly blown head gasket may allow engine coolant and oil to mix. A cylinder leakage test involves putting an amount of compressed air into the cylinder with the intake and exhaust valves closed and see how much and wear the air leaks out.