If you are referring to the engine cover, a crack will hurt nothing. It directs air around the engine to help keep it cool. If you are referring to the valve cover then the crack may allow oil to seep out, and will need to be repaired or replaced.
The oil filter is located at the bottom of the engine. It can be remove with an oil filter wrench. Do not remove the engine top cover unless you need to repair something very major.
Does it have 2 lines coming from the top of the oil filter, and going to the radiator. If so that is the oil cooler. You need to replace the RADIATOR Those 2 lines go into the radiator so it can cool the oil, and the tubes are leaking oil into the coolant.
The oil filter location is on the top of the engine. Just look on the top and you will see a cylinder like area that you need a special tool to take off. If you are looking at the engine it will be on the right side of it near the top.
Yes, you can mix them.
No, you add oil at the oil fill cap on top of the engine.
Through the oil filler cap on top of the engine
Open the OIL FILLER cap--on the top of the engine- and add oil.
On the top of the engine there is a cap on the top of the valve cover pan. Unscrew the cap and add oil there.
On newer cars it is a copy on the top of the engine marked "OIL".
No. Use the recommended oil, otherwise you might shorten the life of your engine. Engines are expensive.
No, use only the weight oil as recommended by the manufacture.