Some BMW E90 engines are known to consume oil at a higher rate. Drivers may need to top up oil frequently — this should not be ignored.

Symptoms

• Blue smoke from exhaust
• Oil level drops fast
• Performance loss

Main causes

• Worn piston rings
• Leaking valve stem seals
• Worn turbo seals
• Faulty PCV valve

Solutions

• Compression/leak-down test
• Replace valve stem seals
• Turbo seal repair
• Replace PCV valve
• Use high-quality oil

Advice

Track oil consumption. Early repair avoids catalytic converter and engine damage.