It sounds like you have some maintance to get caught up on. You probably do need a ccv. This controls pressure in the crank case and if it gets plugged the pressure will find the weakest link to get out, or blow the valve cover gasket. I think on this it's called an upper head gasket but you know what I mean. A bad ccv also decreases fuel mileage as there's added resistance in the crank case. Old oil will also decrease mileage as it creates more friction. As for the power drain when using windows and other 12 volt power things in the car. This can be a sign of a weak battery, have it load tested, or poor ground (pretty hard to find). Sometimes regreassing the window tracks and motors helps. Alternators don't really get weak they either work or they don't work. As for tune up in a can products I have used them before and they do have a place. They are not a fix all however. What I do is with a warm engine so the oil is thinner I will add a can of seafoam let it run for about ten mins then drain the oil while it is still warm. I have also under pressure injected seafoam into the injector rail to clean the injectors. It appears the 318 has an issue with carbon buildup on the injectors. When I did my coolant connectors and had the injector out I soaked them in seafoam to remove the carbon build up. As for plugs I'm guessing I had factory plugs still in my 96 when I got her. and they were pretty bad looking. I felt a noticable power gain when I changed them. Good luck |