Has this ever happened to you? You are driving down the road and start smelling something burning. You look in your rear view mirror and see blue smoke. When you stop at the nearest gas station to check the oil level, it seems okay. San Francisco BMW Repair suggests that there could be many reasons, here are the top three.
When you pull the dipstick again at home, you find that the level is lower than it should be. It confirms that your car is burning oil, but why? One possible reason is that oil is leaking somewhere, possibly from a worn or broken seal, and dripping on a hot engine component, such as a valve cover or the exhaust manifold. Once the oil touches those, you begin to smell something burning.
Another indicator is black puddles gathering under your car or bluish smoke seeping from under the hood. It is a common phenomenon for cars due to age or simple wear and tear.
A second possibility is oil entering the combustion chamber due to faulty or damaged piston rings. When these or the cylinder head valves can’t create a good enough seal, oil sneaks past and gets burned up along with the gasoline. That too gives off a burning smell, but the blue smoke will exit through the exhaust pipe at the back of the car. That can tell you where the problem is.
If the blue smoke appears while you are accelerating, then the problem is the piston rings. If it shows up while you are decelerating, then it is most likely the cylinder head valves at fault.
The third suspect is a worn Positive Crankcase Ventilation (PCV) valve. When this valve is working properly, it keeps prevents gas buildup in the crankcase by expelling it. When the PCV valve is not working or wears out, that same gas gets a chance to increase until it puts pressure on the gaskets keeping the oil out. Once the oil gets past those gaskets, it is burned off, giving you the burning smell and blue smoke.
The best way to get the problem fixed depends entirely on what the cause is. Some of the leaking seals and gaskets can be fixed with a simple additive to replenish them. If that fix doesn’t work, the leak is major, or if the oil is coming from somewhere else, then you want to have a mechanic fix your vehicle. What may seem like a minor issue now can easily become a bigger and more expensive problem later.