What Causes Excessive Engine Oil Consumption?
2 Answers
Excessive engine oil consumption can be attributed to the following reasons: 1. High blow-by gas in the crankcase, causing oil to be blown into the atmosphere through the ventilation pipe; oil cooler leakage; excessive clearance between the piston and cylinder wall; piston rings being misaligned, stuck in the ring groove and losing elasticity; incorrectly installed twisted or tapered rings losing their oil-scraping function and instead pumping oil into the combustion chamber; damaged valve stem seals; failed turbocharger sealing rings causing oil leakage; and air compressor oil blow-by. 2. Blue smoke from the exhaust pipe indicates incomplete combustion due to oil entering the combustion chamber. There are two ways oil can enter the combustion chamber: (1) Oil from the oil pan can enter the combustion chamber upward through a scratched or severely worn cylinder wall; (2) Poor sealing of the intake valve stem seals on the cylinder head allows oil to be sucked into the combustion chamber from the cylinder head through the intake valve.
Excessive oil consumption is giving me a headache, and my old Cadillac is a prime example. After 20 years of driving experience, I've learned that this is mostly an internal engine issue, such as worn piston rings allowing oil to leak into the combustion chamber and burn off, with blue smoke from the exhaust pipe being a telltale sign. Aging valve stem seals are another culprit, as deteriorated rubber fails to seal properly. I've fixed this a few times by replacing the seals, which provides temporary relief. External oil leaks shouldn't be ignored either—a cracked oil pan gasket or loose bolts can leave obvious oil stains on the ground after parking overnight. Driving habits play a role too; frequent long-distance high-speed driving raises engine temperatures and accelerates oil consumption. Checking oil levels more often and using the correct viscosity oil can buy some time, but if it's severe, it's best to visit a professional shop for a thorough repair before the engine gives out.
