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Oil Consumption Diagnosis
 
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Pelican Technical Article:

Oil Consumption Diagnosis

Nick Czerula

Time:

2 hours2 hrs

Tab:

$20

Talent:

****

Tools:

Flashlight

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.

Viscosity

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.


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Comments and Suggestions:
Alex Comments: Do N14 turbochargers have a serviceable internal seal. I've see some oil inside the intercooler pipes which potentially points to an internal turbo leak, but not sure if there are other reasons for oil there. The oil feed line is not leaking. I've serviced this seal in another turbo car I owned but I've never seen the part advertised for my 2008 Cooper S. Thanks!
April 10, 2017
  Followup from the Pelican Staff: The turbochargers don't have a rebuild kit as far as I know. Give The Pelican Parts parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
 
Brian Comments: I think I may have found a cause for the oil usage. The turbocharger looks like it is leaking. The only wet spot I saw under the car.
What do you think?
March 21, 2017
  Followup from the Pelican Staff: Good catch! I would clean the area, then look for light colored clean oil leaking. Also, remove the charge air duct and confirm the oil is not coming from inside the turocharger.

it is common for the oil return(at bottom) line to leak. - Nick at Pelican Parts
 
Brian Comments: I was using Castrol 5w30 but since the usage increased I've been using 5w40. The owners manual gives that weight as an alternative. I just took delivery of enough Driven DT40 to try that. To see if there is any improvement by using a higher quality lubricant as suggested by a staff person there at Pelican. We'll see what happens or doesn't.
March 8, 2017
  Followup from the Pelican Staff: I don't think the higher weight will help use issues. usually doesn't. - Nick at Pelican Parts  
Brian Comments: A worn engine? What kind of piece of crap am I running? I've heard that Peugeot's with this engine are having the same problems with it. It's most likely a design flaw that neither company will admit to. The newer MINIs that still use that engine in later model years don't have this problem. Why has BMW not issued a recall to correct the situation for those of us stuck with these 2cycle wonders?
March 8, 2017
  Followup from the Pelican Staff: The engines do not hold a lot of oil to begin with. Add that to the long oil change interval and you end up with oil being used or engine wear from low oil levels. If you increase you oil change interval, you can prevent oil use and wear.

I don't know where BMW or MINI stands on the subject. - Nick at Pelican Parts
 
Brian Comments: Do you think that putting a better oil will get it back to using a quart at 1000 miles?
That Driven oil is pretty expensive. I'm willing to try it rather than spend a bigger fortune at the dealer.

My 85 Jetta Coupe has been on Mobil 1 5w50 since 1987.
Once I tried 5w50 Syntec and it used some oil. Otherwise never unless there was a leak.
March 3, 2017
  Followup from the Pelican Staff: use the recommended oil from MINI. If there is an oil use issue, it may be a worn engine. - Nick at Pelican Parts  
Brian Comments: I'm using Castro's EDGE, 5w40 since the last oil change. Like AJK same thing, soot on the tailpipes but not black smoke that I've noticed..
February 28, 2017
  Followup from the Pelican Staff: Soot may be normal. Is there smoke and what color and when / how long does it smoke? - Nick at Pelican Parts  
Brian Comments: I have the latest version of the valve cover installed already.
February 28, 2017
  Followup from the Pelican Staff: That connection was not eliminated, they will not alter an emission component that way. Some European nations don;t require it, you may have seen photos from that. - Nick at Pelican Parts  
Brian Comments: Didn't MINI change the emission controls to eliminate that hose on the passenger side of the engine? All it was doing was sucking the oil into the intake manifold and coking the valves.
February 27, 2017
  Followup from the Pelican Staff: They may have found $ome way around the EPA re$triction$, if you know what I mean... - Casey at Pelican Parts  
Peter Comments: Castor-oil is what Mini recommends. I may try a different oil. I also read that Mini changed the way the valve cover is designed as that may have been the cause of high oil consumption. I will call them to see if that is true.
February 27, 2017
  Followup from the Pelican Staff: Excellent! Please let us know what they say! - Casey at Pelican Parts  
Peter Comments: I have a 2008 S model and I can easily hear when the engine is low 1/4 quart of oil. I use at least 1 quart per 1000 miles at minimum and have just started logging it. On the last two oil changes I added BG 109 EPR engine flush and the oil was extremely black with carbon. The engine sounded a lot smoother after the flush. My mechanic accuses me of using lower grade gasoline, but I run 91 octane. Perhaps I am not running the engine above the 3500 RPM very much as this may burn off any carbon deposits. The computer fuel mix is suppose to adjust for this so I'm not sure how I have so much carbon build up. I replace the spark plugs as required and I'm surprised how much wear is on them at 30K miles of driving. I have no oil leaks from the engine and I never see smoke coming out of the exhaust pipe when shifting gears. The amount of oil consumption is disturbing and I continuously check and add oil. Perhaps I'll take it if for an emissions test and see how much oil is in the exhaust. I run Castor-oil full synthetic 5W-30 year round.
February 26, 2017
  Followup from the Pelican Staff: You should try another oil. That stuff has been known to cause issues. I have seen oil consumption greatly reduced when changing to a higher quality oil like Driven DT-40 5w-40, or Motul X-Cess 8100 5w-40. - Casey at Pelican Parts  
Brian Comments: My MINI has always used oil. In the last year I had it checked out by the dealer. They told me where some leaks were. They changed the front crankshaft seal. I changed the oil pan gasket, VANOS solenoid and gasket, the valve cover and it is using a quart at about 500 miles. I hear there is a class action suit about this. However, I've read on the British forum that Peugeot, who's gem the s engine is, has a kit that replaces the hose on the passenger side of the valve cover with a plug there and one to the intake manifold where the other end of the hose attaches with positive results. Do you guys know any thing about this?
February 24, 2017
  Followup from the Pelican Staff: I don't think that would be legal for USA EPA emissions. We are not supposed to alter any emissions control system. I would recommend changing to Driven DT40 engine oil. I have seen the oil consumption greatly reduced just from switching oils. - Casey at Pelican Parts  
Bob Phoenix Comments: Your article says "...most manufacturers consider the consumption of one quart of oil per 1000 miles or longer acceptable..."
I am replenishing my '07 "S" with a quart nearly every 1000 miles. Last oil change 70K Mi. I also replaced the plugs. fine wire center electrode type When I pulled number four cylinder plug, there was no ground electrode. It was gone all the way up to the bottom thread. I bought the car used and I don't know when this happened.
My questions are these; Should I be concerned that my cylinder wall is scored because of the remnants of the electrode and that is causing excessive blow by and increased oil consumption? And, can I do a compression test to see if the number four is scored
February 5, 2017
  Followup from the Pelican Staff: You can perform a compression test and leak down. I would assume you would have a misfire is there was an issue. - Nick at Pelican Parts  
AJK Comments: I have a 2009 Mini Cooper S. It seems like I'm adding 1/2 a liter to a full liter of oil at every third fill up. I don't see black smoke coming from the car but there is a soot build up on the tail pipes.
I notice an increased oil consumption when I run the car in "Sport Mode." I'm wondering if this has to do with a bad seal on the Turbo Charger?
October 27, 2016
  Followup from the Pelican Staff: Could be, or a faulty oil separator. - Nick at Pelican Parts  

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Page last updated: Wed 5/24/2017 03:04:16 AM