I used to have an old car with the same problem. Mechanic told me that I have worn out piston rings. That is why some of the combustion pressure in the piston cylinder is going under the crankcase (should be all pressure going out in the exhaust pipe) causing the oil/steam pressure to go out of the valve cover. My only suggestions are:
1. When you change oil, use a thicker gauge. I used number 40. Do not use the thin oil 5W30 nor 10W30.
2. Add oil additive that thickens the oil or that helps lessens oil burning in the piston cylinder or the one that coats piston cylinder.
3. I did not connect back the pressure hose to the air cleaner. I bought a long hose (thickness same as the pressure hose), remove the old pressure hose from the valve cover and insert this new long hose and guide the other end all the way to the bottom beside(outside) the engine. 2 to 3 inches below the bottom of the engine. So that the oil will just leak to the road. Make sure to strap the hose so that it would not touch any moving parts or exhaust pipe. It works for me until I can afford to buy a better car.
4. Check your oil everyday before you use it. I believe your engine eats/burns oil.
5. Use spark plugs that are good in oil burning. I was recommended with Champion brand spark plugs.
If your engine is misfiring (rough engine). Check one of your spark plugs that is soak with oil. Replace only that one, not all. So, carry spare spark plugs.
Sunday, August 26th, 2007 AT 8:05 PM