When oil consumption becomes abnormal
Every engine uses a small amount of oil, and each manufacturer states the acceptable level of consumption in the service book. The warning signs are: needing to top up regularly between oil changes, noticing the level dropping noticeably from one fill to the next, or seeing blue smoke from the exhaust.
Where is the oil going?
| Sign | Likely cause |
|---|---|
| Stains under the car, oily engine | External leak: sump gasket, rocker cover gasket, lip seals |
| Oil in the intake hoses, blue smoke under acceleration | Turbo or crankcase breather |
| Blue smoke on start-up and during acceleration | Valve stem seals |
| Persistent blue smoke, fouled spark plugs | Worn piston rings or pistons |
The risks
The main danger is running low on oil, which triggers the oil pressure warning light and can lead to engine failure. Burnt oil also clogs the catalytic converter and diesel particulate filter, and worn piston rings cause a loss of compression and power.
Can you keep driving?
Yes, provided you check the level at every fill-up and keep a supply of the recommended oil in the boot. Never let the level drop below the minimum mark on the dipstick.
Repair or replace?
A leak, a crankcase breather or a turbo can be dealt with without stripping the engine. Worn piston rings indicate internal wear: reconditioning requires the engine to be dismantled and often costs as much as an exchange. A reconditioned engine on an exchange basis, supplied as a bare engine, accepts your ancillaries and comes with a warranty of up to 24 months.
