What are the reasons for engine oil consumption?
4 Answers
Engine oil consumption can be attributed to the following specific reasons: 1. Poor valve sealing. Generally, if an engine burns oil, the first step is to check whether the valves and valve oil seals are functioning properly. Next, inspect the clearance between the piston rings and cylinder liners. Replacement may be necessary if issues are found. 2. Excessive clearance between the pistons, piston rings, and cylinder liners. This situation may require replacing the pistons, piston rings, lower cylinder liners, reboring the cylinders, replacing the valve and valve oil seals, grinding the crankshaft, and replacing the big and small end bearings. Essentially, all damaged parts of the engine need to be replaced with new components. After a major overhaul, the engine will require a break-in period similar to that of a new car.
Engine oil burning is a common issue I encounter, primarily due to internal component wear. If the piston rings age or break, the sealing performance deteriorates, allowing oil to sneak into the combustion chamber and burn. When the valve stem seals become as brittle as a cracker and split, oil drips down the valve stems, which is another headache. The turbocharger's sealing rings are also prone to failure first, and once damaged, oil escapes with the exhaust gases. Additionally, cylinder walls worn into a sandpaper-like texture or a stuck crankcase ventilation valve can cause a sharp increase in oil consumption. These problems usually result in blue smoke from the exhaust and a noticeable drop in power. It's advisable to regularly check the oil dipstick and head to the repair shop immediately if abnormal oil consumption is detected, rather than waiting until the engine completely fails.
My old car used to burn oil badly, and later I found out the reasons were quite complex. Prolonged delays in changing the oil led to excessive sludge buildup, which aggravated internal wear. Driving habits also matter—constantly revving the engine to high speeds causes overheating and accelerates the aging of rubber seals. Choosing the wrong oil viscosity is another culprit; oil that's as thin as water evaporates more easily under high temperatures. The worst offender was a low-quality air filter, which allowed dust to enter the cylinders and scratch the cylinder walls, letting oil slip in and burn. Since I started sticking to a strict 5,000-kilometer maintenance schedule and switched to full synthetic oil, the situation has improved significantly. It's a good habit to check the dipstick every two weeks—if the oil level drops more than a quarter below the lower mark, top it up promptly.
Older engines burning oil are mostly due to worn-out components. Valve stem seals made of rubber become brittle and crack after ten years, failing to contain the oil. Worn piston rings increase the gap with the cylinder walls, allowing oil to sneak upwards. The metal sealing rings in turbochargers are often the first to fail, sucking oil into the intake when damaged. A clogged crankcase ventilation system can build up pressure, forcing oil out. For these older vehicles, checking oil levels twice a month is crucial. If consumption spikes, immediate inspection is needed—replacing valve seals or piston rings can save significant repair costs.
