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Q: Oil evap and low engine effiency

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My car engine efficiency is 68%, i was told the car evaporates oil slightly. The car also shakes a bit when idling even after I changed the engine mounts. The previous owner barely drove the car and stored for a long time. Could it be the PVC? Or the cylinder ring ?

My car has 66000 miles.
My car has an automatic transmission.

Hello and thank you for your question. First, oil does not evaporate, but rather oil burns if there are no signs of leakage. Oil consumption is a common thing to see in engines. There are 3 things that will cause oil consumption. One is the PCV (Positive Crankcase Ventilation) valve is plugged up. If the PCV valve is plugged up, then the engine produces too much pressure forcing oil into the combustion chamber. Second is there can be too much oil in the crankcase causing too much pressure inside the engine forcing oil into the combustion chamber. Third is carbon buildup on the piston rings causing the rings to stick and allow oil to be sucked into the combustion chamber. This also can cause the engine to run rough and shake as if there is a slight misfire. I recommend having your engine cleaned out. New oil and filter, and have your engine decarbonized from the inside. You can get injection cleaner or sea foam to clean out your engine. Sea foam is very powerful and should be used in the fuel tank along with the vacuum system. The engine must be at high RPM’s around 3,000 to use sea foam in the vacuum system and the engine must be at operating temperature. Also, make sure that the vehicle is in a clear open area, for there will be a lot of soot smoke from the tail pipe. If you need assistance in your engine issue, seek out a professional, preferably a Your Mechanic professional to help you with your engine.

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