Your car is burning oil primarily due to internal engine wear. The most common culprits are worn piston rings, degraded valve seal seals, or issues with the Positive Crankcase Ventilation (PCV) system. These components are meant to keep oil in the crankcase and out of the combustion chamber where it's burned. When they fail, you'll see symptoms like blue-tinted smoke from the exhaust, a noticeable drop in oil level between changes, and potentially fouled spark plugs.
While some oil consumption is normal (many manufacturers consider a quart every 1,000-1,500 miles acceptable), rapid loss is a sign of a problem. Here’s a quick look at typical oil consumption standards for context:
| Manufacturer | Acceptable Oil Consumption (per 621 miles/1,000 km) |
|---|
| Audi / Volkswagen | Up to 0.5 quarts |
| BMW | Up to 1.0 quart |
| General Motors (GM) | Up to 1.0 quart |
| Subaru | Up to 1.0 quart |
| Toyota | Up to 0.4 quarts |
Diagnosing the exact cause is key. A clogged or faulty PCV valve is often the easiest and cheapest fix. If it's stuck open, it creates excess crankcase pressure, forcing oil vapor into the intake to be burned. Replacing this $15-$50 part can sometimes solve the issue entirely.
More serious are worn internal engine parts. Piston rings seal the gap between the piston and cylinder wall. Over time, they wear down, allowing oil to seep into the combustion chamber from below. Similarly, valve seals prevent oil from leaking down the valve stems into the cylinders; when they harden and crack, oil drips in and burns. Fixing these requires significant engine work, often costing thousands of dollars. The severity of the oil burning will determine if you can just top off the oil regularly or need to plan for a major repair.
