Taken from
Symptoms of Fried Piston Rings - CarsDirect
Common Symptoms of Damaged Piston Rings
Problems with your car engine's piston rings often display symptoms or signs that are similar to other problems with low compression in a vehicle. While the following symptoms are not always attributed to faulty piston rings, they are a good indicator that you should check the rings for wear and to see if they need to be replaced. Here is a list of the most common symptoms for bad piston rings:
White or gray exhaust smoke
Excessive oil consumption
Low power for acceleration
Overall loss of power or poor performance
If you believe your vehicle has faulty piston rings, or if your vehicle is displaying any of the above mentioned symptoms, you will need to have a compression test run on your car's engine. A compression test involves removing one of the spark plugs from your engine and trying to start the engine with a compression gauge attached to the cylinder where the plug has been removed. You can purchase a compression gauge and do the test yourself, or you can take the vehicle to a certified mechanic for an engine diagnosis.