Why does my BMW use oil? BMW oil consumption explained

BMW oil consumption is one of the most common questions from new owners. The car shows a message asking for a litre of oil a few thousand kilometres after a service, and the owner wonders if something is wrong with the engine.

In most cases the answer is no. Every combustion engine uses a small amount of oil, and high-performance engines usually use more than ordinary ones. But high consumption can also be the first sign of a problem. In this guide we explain what is normal, the most common causes of excessive consumption and how to measure it correctly before you decide what to do.

Why every engine uses some oil

A thin film of oil covers the cylinder walls to lubricate the piston rings. With every combustion stroke, a tiny part of this film is burned together with the fuel. Oil also reaches the combustion chamber through the valve guides and through the crankcase ventilation system, which returns oil vapour from the crankcase to the intake.

This means that some oil consumption is part of the normal design of every engine. It is not the same as an oil leak, where oil escapes from the engine and drips onto the ground.

Several factors make BMW engines, and especially M engines, use more oil than an average family car:

• High engine speeds. Engines such as the S54, S65 and S85 rev beyond 8,000 rpm, which increases oil consumption.
• Tight tolerances and low-friction piston rings, chosen for performance and efficiency.
• Turbocharging, where the turbo bearings are lubricated by engine oil.
• Driving style. Spirited driving and track days increase consumption significantly.

A new engine also often uses more oil during the running-in period, before the piston rings have fully bedded in.

What BMW says about normal oil consumption

BMW states in its owner's handbooks that engines consume oil and gives a maximum acceptable figure for each engine. This figure is usually expressed in litres per 1,000 km and depends on the engine and on how the car is driven. You can find the value for your car in the owner's handbook or by asking a BMW service partner.

The important point is that topping up oil between services is considered normal by BMW. The oil level must be checked regularly, and oil must be added when the car asks for it. Many modern BMWs have no dipstick and measure the level electronically. The result is shown in iDrive or in the instrument cluster.

For most owners, a top-up of around one litre between services is not a reason to worry. When consumption suddenly increases, or when the car needs oil much more often than before, it is time to look for a cause.

Common causes of high BMW oil consumption

When BMW oil consumption rises above the normal level, the cause is usually one of the following:

• Crankcase ventilation (PCV) valve. A faulty valve or diaphragm can pull too much oil vapour into the intake. On engines such as the N52, N54 and N55 this is a well-known cause, often combined with smoke from the exhaust and a whistling noise at idle.
• Valve stem seals. Hardened seals allow oil to run down the valve guides into the cylinder, typically visible as blue smoke at start-up after the car has been parked.
• Piston rings. Worn or stuck rings let oil pass into the combustion chamber. Some engines, such as the early N63 V8, became known for this, and BMW introduced service measures for affected cars.
• Turbocharger seals. A worn turbo can push oil into the intake or exhaust, often with blue smoke under load.
• Leaks. Not every litre is burned. Leaking gaskets can lose a surprising amount of oil. Our guide to BMW oil leaks explains where to look.

Finding the right cause is important, because the repair costs range from a small part to a major engine job.

How to measure oil consumption correctly

Before deciding that an engine uses too much oil, measure the consumption carefully. Messages and impressions are not enough.

A simple and reliable method:

1. Fill the oil to the maximum mark, measured on a warm engine and level ground, using the electronic measurement or the dipstick.
2. Note the mileage.
3. Drive normally for at least 1,000 to 2,000 km.
4. Measure again in the same conditions and top up to the maximum, noting exactly how much oil you add.
5. Divide the amount added by the distance driven.

Repeat the test over a few thousand kilometres to get a reliable average. Write down your driving conditions as well: a week of motorway driving, a track day or many short trips will each give different results.

A BMW service partner can also carry out an official oil consumption test, which is often required before any warranty or goodwill claim is considered.

Warning signs that need attention

Some signs suggest that high oil consumption is caused by a real problem:

• Blue smoke from the exhaust, especially at start-up or under acceleration.
• Oily spark plugs or misfires on one cylinder.
• Oil in the intake tract or on the turbo inlet.
• A sudden increase in consumption compared with previous months.
• A whistling noise at idle combined with a rough idle, typical of a failed PCV valve.
• Oil spots under the car, which point to a leak instead of burning.

Never ignore a low oil level warning. Driving with too little oil can damage bearings, turbochargers and VANOS units very quickly. If the warning appears, stop as soon as it is safe, check the level and add the correct oil.

Choosing and carrying the right oil

When topping up, always use an oil that meets the BMW approval for your engine, such as BMW Longlife-01, Longlife-04, Longlife-12 FE or Longlife-17 FE+. The required specification is listed in the owner's handbook. Our article on BMW M engine oil explains the different approvals in more detail.

Many owners carry a one-litre bottle of the correct oil in the boot, so they can top up when the car asks for it. Mixing approved oils of the same specification in small amounts is not a problem.

Shorter oil change intervals than the maximum allowed by Condition Based Service are also popular with enthusiasts. Fresh oil keeps its properties better, and regular checks help you notice changes in consumption early.

When should you worry?

BMW oil consumption is normal as long as it stays within the limit in the owner's handbook and does not change suddenly. A high-revving M engine that needs a litre every few thousand kilometres, especially when driven with enthusiasm, is usually healthy.

You should investigate further when consumption rises quickly, when you see smoke, when the spark plugs are oily or when oil is clearly leaking. In these cases a specialist can check the PCV valve, perform a compression or leak-down test and inspect the turbochargers.

When buying a used BMW, ask the seller how often the car needs oil and check the service history. A car that has been regularly topped up and serviced on time is a much better buy than one where nobody has checked the oil level for years.

BMW oil consumption at a glance

Item	Details
Is some oil consumption normal?	Yes, BMW considers it normal for every engine
Where to find the limit	Owner's handbook or BMW service partner
Engines using more oil	High-revving M engines and turbo engines
Most common causes	PCV valve, valve stem seals, piston rings, turbo seals, leaks
How to measure	Fill to max, drive 1,000+ km, measure what you add
Warning signs	Blue smoke, oily plugs, sudden increase, oil spots
Correct top-up oil	BMW Longlife approval listed for your engine

Frequently asked questions

Is it normal for a BMW to use oil?

Yes. BMW states that engines consume oil and gives a maximum figure for each engine in the owner's handbook. Topping up between services is normal.

How much oil consumption is too much?

More than the limit in your owner's handbook, or a sudden increase compared with before. Measure it over at least 1,000 to 2,000 km before deciding.

Why does my BMW smoke blue at start-up?

Usually because of worn valve stem seals, which let oil run into the cylinders while the car is parked. A failed PCV valve can also cause smoke.

Can I mix different engine oils when topping up?

Small amounts of oils with the same BMW approval can be mixed. Always use an oil approved for your engine.

Do BMW M engines use more oil?

Usually yes. High-revving engines such as the S54, S65 and S85 use more oil, especially when driven hard or on track.

Sources

• BMW owner's handbooks – engine oil level, consumption and approved oils
• BMW service information – crankcase ventilation and engine maintenance