Mini Cooper Parts Catalog Mini Cooper Accessories Catalog Mini Cooper Technical Articles Mini Cooper Tech Forums
  Search our site:    
View Recent Cars  |   Cart  | Project List | Order Status | Help    
 >  >
Oil Consumption Diagnosis
Bookmark and Share

Pelican Technical Article:

Oil Consumption Diagnosis

Nick Czerula


2 hours2 hrs







Applicable Models:

R52 MINI Cooper Convertible (2007-08)
R52 MINI Cooper S Convertible (2007-08)
R56 MINI Cooper Hatchback (2007-11)
R56 MINI Cooper S Hatchback (2007-11)
R57 MINI Cooper Convertible (2009-11)
R57 MINI Cooper S Convertible (2009-11)

Parts Required:

Engine oil

Hot Tip:

Work with a cool engine

Performance Gain:

Repair oil leak

Complementary Modification:

Replace oil

The engines used in MINI R56 cars are MINI New Generation engines. MINI New Generation engines are 1.6 liter, with turbocharged and normally-aspirated versions. All aluminum two-piece crankcase construction keeps weight down, while technology like adjustable camshaft angle and variable valve lift help to keep the engines efficient.

Keep in mind that when your car was serviced before, parts may have been replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have, so be prepared with different size sockets and wrenches.

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If you're working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Do not work on your vehicle if you feel the task is beyond your ability.

Vehicle models change and evolve, as they grow older, so the vehicle shown in our illustrations may vary slightly from yours. If something seems different, let us know and share your info to help other users. Do you have questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.

Measuring Oil Consumption

Internal combustion engines use oil to lubricate internal moving components. The oil forms a thin film between metal parts such as bearings and bearing journals, therefore preventing the metal parts from wearing out due to friction.

Engine oil also plugs up the extremely thin gap between a seal lip and its sealing surface. Similarly, it seals up the gap between piston rings and cylinder walls.

One further function of engine oil is as a coolant for the hot engine parts it contacts.

All engines normally consume some engine oil during operation. A well-broken-in engine operated under normal conditions may be able to travel up to 6000 miles without a discernible drop in the engine oil. But most manufacturers consider the consumption of one quart of oil per 1000 miles or longer acceptable. Oil consumption that exceeds 1 quart per 750 miles is considered excessive and in need of additional diagnosis.

Before starting such diagnosis, it is worthwhile understanding the role and function of engine oil in more detail.


The recommended viscosity of engine oil is dependent on ambient temperature and the normal operating parameters of the engine. Oil is more viscous ("thicker") at low temperatures and less viscous ("thinner") as the temperature rises. In cold weather, when starting a cold engine, the oil needs to flow easily both in order to not impede engine operation and also so it can flow more easily through the oil pump and oil passages, quickly reaching critical parts that need lubrication. As the engine warms up to operating temperature, the oil is required to keep a certain viscosity so that the oil film between moving metal parts remains intact. Multi-viscosity lubricants are designed to be thin when cold and not thin out excessively as they heat up.

A number of factors need to be considered here. In an older engine with worn components, the gaps between moving parts are larger, and the oil needs to be more viscous to fill the gaps. A freshly manufactured engine will have very small gaps between components. A viscous oil might not be able to force its way into those gaps, causing additional wear and tear. So the recommended viscosity of oil is very much dependent on the age of the engine.

In a turbocharged engine the turbocharger shaft may spin in excess of 10,000 rpm. The oil seal around the turbocharger shaft inevitably seeps small amounts of oil into the turbo air stream. The viscosity of the oil is critical for keeping the amount of oil seepage low.

In hot climates the recommended multi-viscosity rating is bumped up in order to accommodate the higher general range of temperatures encountered. In very cold climates, the recommended rating is bumped down. If you do not adhere to the recommended range multi-viscosity oil, you are liable to either damage your engine or cause excessive oil consumption.

Crankcase ventilation

In addition to being circulated via the oil pump, the motion of the crankshaft in the crankcase splashes the oil passages with engine oil. This splashed oil and the oil sprayed out past the bearings and bearing-journal gaps forms a fine oil mist inside the crankcase, which condenses on the cylinder walls and is wiped down into the sump by the action of the piston rings. Some of this oil, as mentioned before, serves to seal the rings against the cylinder walls. Some also escapes past the rings. If the rings are well-seated in the cylinders, the amount of oil lost past the rings is minimal.

The movement of pistons in the crankcase as well as the normal heating up of the engine produces pressure in the crankcase. In older engines this pressure was vented to the outside in order to prevent the crankshaft seals from blowing out. "Downdraft" crankshaft ventilation was among the first automotive systems to be controlled in California in the 1960s in order to begin reducing automotive pollution. The downdraft pipe was required to be routed to the air-cleaner where the excess oil vapor was sucked into the carburetor and burned in the cylinders.

A more sophisticated system, positive crankcase ventilation (PCV) was phased in by manufacturers. A vented hose from the intake manifold, often with a spring-loaded valve, was connected to the crankcase to maintain a steady state of low vacuum. Various off-shoots of this system are used now. The oil that is sucked into the vent hose is allowed to condense on a series of baffles and then dripped back into the crankcase, so that total oil loss from this system is kept to a minimum. Engine oil consumption increases significantly if the crankcase ventilation system is defective.

Oil Dilution

Engine oils are designed to absorb and neutralize a number of contaminants. The contaminants are combustion byproducts forced past the piston rings from the combustion chambers. Fresh engine oil has enough additives to neutralize the mostly acidic compounds forced past the rings. Also, being fresh and relatively viscous, it seals the rings reasonably well. However, some unburned or partially burned fuel also comes past the rings and dilutes the oil. Eventually, the combination of diluted oil and depleted additives causes the oil to lose its ability to seal well. More contaminants are allowed into the crankcase and the oil itself seeps out past the rings (and other orifices) more quickly. Hence, you have higher oil consumption.

Mechanical leaks

There are a number of places that engine oil can leak out:

Crankshaft seal at the front (pulley side) of the engine - This can manifest itself if oil is on the front of the engine or, possibly, oil gets on the engine belt(s).

Crankshaft seal at the rear (transmission side) of the engine - Oil may be dripping out of the bellhousing. In a manual transmission vehicle, the clutch may be oil-contaminated.

Camshaft(s) seal(s) in some engine designs may leak oil onto the exterior of the engine.

The seal at the turbocharger (if equipped) is a potential source of leaks as the engine ages. This is usually hard to detect, but a thin coating of oil on the inside of the turbocharger air ducts is a potential giveaway.

The valve cover gasket and sump gasket can also become brittle and leaky with age.

Valve seals inside the valve cover can become hard and brittle and leak oil into the intake or exhaust ports.

Piston rings may get worn out and leak oil into the combustion chambers.

Oil consumption from valve seal or piston ring wear often (not always) manifests as blue smoke out the tailpipe.

Keep in mind that leaks from seals and gaskets become more problematic if the oil becomes diluted. Also, if there is a malfunction of the crankcase ventilation system and pressure builds inside the crankcase, seals will leak more or may blow out altogether.

Additional Considerations and Summary

Up to about 6000 miles of use, an engine is considered to be in its "break-in" period. This is when the piston rings seat in. Oil consumption during this period may be high. The driver needs to be conscientious during the break-in and check the oil frequently. Once the engine gets past the 6000 mile break-in, a baseline for oil consumption needs to be established. If there is an abrupt increase in oil consumption, it makes sense to consider the factors explained in this article.

Other factors leading to high oil consumption:

Very high speed driving and pulling a heavy load can contribute to additional oil consumption.

A sudden heat wave, continuous city-driving, and use of fuel with high olefin content may all contribute to high oil consumption.

If the engine is overfilled, oil seepage past the rings due to excessive oil splash causes additional consumption.

A rough measure of oil consumption is to check the dipstick (or electronic oil level sensor) periodically. A more accurate way to measure oil consumption is to change the oil, filling the engine to the correct level. Then drive the vehicle 1000 miles or until a low oil warning (such as dipstick indicating one quart low) is received. Then drain the oil and measure the amount of oil again to pinpoint the consumption level.

Here is a summary of potential causes of high oil consumption:

Incorrect viscosity oil

Crankcase ventilation system faulty

Oil diluted or contaminated

Mechanical leaks: Seals, piston rings, valve seals, gaskets

High speed driving, heavy loads

Heat wave, city driving, incorrect fuel

Engine overfilling

Use your engine oil dipstick (red arrow) to monitor engine oil level.
Figure 1

Use your engine oil dipstick (red arrow) to monitor engine oil level. I suggest checking it at every fuel tank fill up. Oil level should be between the two marks on the dipstick. If you have to fill the engine, keep a journal of how much you add and when. This will help you track oil use.

Bookmark and Share

  Search our site:    

View Cart & CheckOut | Project List | Order Status |  Help    


[Home] [Customer Service] [Shopping Cart] [Project/Wish List]
  [Privacy Statement]  [Contact Us] [About Us] [Shipping] [Careers]

Copyright © Pelican Parts Inc. -    DMCA Registered Agent Contact Page

Page last updated: Sat 10/22/2016 02:55:00 AM