Passenger car engine oils
Engine oil warning signs — and what the colour tells you
Engines usually warn you before serious damage. Knowing the signs and how to read a dipstick takes two minutes and can save a major repair bill.
Signs of low oil
- The oil warning light (oil-can symbol) comes on: oil pressure is low. Stop safely and switch off the engine straight away.
- Ticking or knocking from the engine, especially at start-up.
- A smell of burning oil inside the car.
- Engine temperature running higher than usual.
Read the dipstick properly
Park on level ground and wait a few minutes after switching off. Pull the dipstick, wipe it, push it fully back in and pull it out again. The level should sit between the minimum and maximum marks.
What the colour means
- Amber and clear: fresh, healthy oil.
- Dark brown to black: the oil is working and holding contaminants. Darkening alone is not a fault, especially in diesels — mileage and time decide the change.
- Milky or foamy: coolant may be entering the oil, for example through a head gasket. Have it checked immediately.
- Shiny metal particles: a sign of internal wear that needs a mechanic.
Thickness and smell
Oil that is very thin and smells of petrol may be diluted with fuel — common with short city trips or fuel-system faults. Oil that has become thick and tar-like is overdue and must be changed now.
Quick answers
The oil light came on — can I keep driving?
No. Stop at the first safe place and switch off. Driving with low oil pressure can seriously damage an engine within minutes.
Does black oil mean I must change it?
Not necessarily. Darkening is normal; the change interval is set by mileage and the manufacturer.
What does milky oil mean?
Usually water or coolant in the oil. If the coolant level is also dropping, have the head gasket checked.
Need the right product?
See our passenger car engine oils range, or ask our sales team for a recommendation and price.
