Hello folks,

I searched but I could not find right posts, if it can be covered already then sorry about this.

I put around 7900 miles on my 2008 MCS (6 spd) and I can smell gasoline fume in the engine oil. Yesterday, I took out the oil dip stick to check my engine oil. When I was looking at it up close, I smell the gasoline. I have not changed the engine oil yet and should I be concerned about this?

Thanks in advance.

 

Ha funny you should mention this. I smell gas too at 36,000 kilometers. It has been a few years since I was a grease monkey I could not recall if this was normal or not. I would beleive if the oil smells like gas then there is gas in it which will break down the oil thus ruining our engines.

 

That could indicate bad rings (gas getting past the rings into the oil). Worn rings would be VERY unusual for a relatively new car. Could be there is one broken.

How's your MPG? Is there any smoke from the exhaust?

I'd get it checked for peace of mind.

 

Could also be the Direct Injection diluting the oil with gas.

 

How is the car used? If your using your MCS for just short trips you may not be getting the oil up to operating temp enough to burn off all the contaminates in the oil.

 

How would this happen?

 

25 minutes 18 miles in the morning and 35 minutes 18 miles in the afternoon. And it will be 80% freeway, 20% city.

 

There is a strong chance that you have bad piston rings. If gas is getting past the rings into the oilpan, then you should have oil burning in the cylinder too.. warmup you engine & check for white smoke --> very clear indication that engine's burning oil

 

I thought blue smoke was oil, white was head gasket? heres my car, she smells like gas too in the oil....AMONG NUMEROUS OTHER PROBLEMS.
http://www.youtube.com/watch?v=KxLnl0NaWT8

 

matty125, that looks bad, but mine does not have blue smoke like yours.

 

Pure white smoke is coolant burning (head gasket problem), bluish tinted smoke is oil.

 

In the old days of carburetor-equipped engines, fuel was essentially "dumped" into the intake airstream at low pressure, like 5-8 psi, and then sucked into the engine by the engine's vacuum.

With modern fuel injection systems like the first-gen MINI, the pressure was higher, around 80-100 psi, and the fuel was injected just upstream of the intake valves. But the fuel was still drawn into the engine either by engine vacuum alone, or with the help of a relatively low-pressure supercharger or turbocharger (15-30 psi).

But with direct-injection systems, the fuel is injected directly into the combustion chamber, at pressures up to *2000 psi* or more. At this pressure, the only thing keeping this fuel from shooting directly past the pistons into the crankcase are the piston rings.

Problem is, piston rings seal best *after* the air/fuel mixture has already ignited. This is because a small amount of the burning air/fuel mixture gets between the piston and the ring, forcing the ring outward against the cylinder wall and improving sealing. But until the mixture ignites, the only thing holding the rings against the cylinder wall is the spring tension of the rings themselves.

Fuel dilution is a common problem with direct-injection engines, because the fuel is being introduced at such a high pressure, and the rings can't fully seal without the help of the combustion gases. The BMW 335/135 engine is having the same issues. Direct-injection is great for power and fuel economy, but it makes it a lot harder to avoid diluting the oil with raw fuel.

 

Thanks for the explanation. All the more reason to change oil more often than every 15K (IMHO). Although I changed my oil at 1500 and 8000 miles and did not get a sense of gas smell in the oil.

 

I emailed MINI service manager;

my email
"I put around 7900 miles on my 2008 MCS (6 spd) and I can smell gasoline fume in the engine oil. Last week, I took out the oil dip stick to check my engine oil. When I was looking at it up close, I smell the gasoline. Should I be concerned about this? or may have a bad piston rings?"

and he said
"My technician does not believe anything to be abnormal from what you describe on your e-mail. There are many fail-safe's built into your vehicle to prevent any catastrophic breakdowns. According to the MINI technicians there is no reason to be alarmed. The likelihood of fuel and oil mixing is very, very slim."

hmm, I may not have to worry too much. And Thanks for the explanation ScottRiqui.

 

I can smell gas to the oil dipstick in every car I have ever checked brand new or older that is why I don't believe any of the myths to be true about that. I think some peoples noses are more sensitive than others.

 

fail safe smail safe....what do they say about the MINI death rattle? All cars can offer catstrophic failure, Hell I think mines on her way

 

What year and model do you have? (Actually, I think I remember that you now have two.) Which one is smoking and has gas-in-oil smell, or both?

Also, how did you break in your car? Several people on NAM have stated that a car should be driven pretty hard during the first 1200 miles, rather than "babied" per the owner's manual. Which did you do?

Inquiring minds want to know...

 

If the dealer doesn't want to look at it, and you want to know if there is fuel in the oil, you can have an oil analysis done for about $25.

My oil had less than 0.5% fuel after 5,000 miles. It should never go above 2%.

 

I have the same problem, I have just about 7900 miles on my car and had a second oil change at MINI at 6200 miles (First at 1500). After that oil change I checked the oil when I got home and I had the same smell that you describe. I didn't think anything of it. I don't have smoke or anything. I would hope that if there was an issue it would be brought to my attention when the oil was swapped out.

 

They don't analyze the oil. It is quite possible that the tech wouldn’t notice fuel dilution unless it ignited on him.

 

You could see these 'Ring' problems coming, after reading about so many new owners trying to get over 500 miles on their first tank of gas.

Although there is no need to abuse or violate 'break-in' Owner's Manual recommendations, wish they would have expanded on "vary speed".

To properly "Seat" your piston rings calls for frequent short acceleration at 75% power, this gas pressure pushes your new rings against the 'cross-hatch' pattern honed into cylinder walls and 'seats' them.

Unfortunately, after the first few hundred miles, the horse has left the barn and there is no way to go back and seat the rings against glazed cylinder walls.

The Only Solution for this is to install New Rings and Re-Hone the Cylinder Walls and start the 'seating' again.

I well remember my fathers GMC Pickup with this condition so long ago,
no warranty fix for that oil burning pig and my General Motors buying dad switched to Ford.

 

Just to keep things straight, the direct fuel injection is running at the pressures quoted above, however, there are two things happening that prevents the fuel from being a 2000 psi squirt gun. First, the fuel is being injected into the combustion chamber near top dead center of the compression stroke. That means the fuel injector has to overcome a lot of pressure in the cylinder to move the fuel into it.

Second, the fuel is being pressed through a nozzle that atomizes it. Think of adjusting a squirty bottle nozzle between fine spray and stream, it takes a lot more trigger pressure to move the water through the fine spray nozzle. After overcoming compression pressure, most of the remaining fuel pressure is spent in atomizing the fuel and the end result of 2000 psi is a rapidly moving, low pressure, fine mist of fuel that must rapidly become a vapor when exposed to the heat of the combustion chamber.

Also, you're right, the piston rings seal the best when under pressure, but that pressure starts when both valves are closed and the compression stroke begins.

With carburators, the fuel didn't "just dump" into the intake manifold. The pressure pushed against a valve connected to a float that sat in a chamber. The chamber held fuel at a level where the low air pressure being generated in the carb's venturi could suck the fuel through the carb jet, in the same way you suck water through a straw. As the fuel level went down, the float lowered, which opened the valve just enough to allow fuel to trickle in. The fuel pressure seen at the jet was never more than ambient air pressure. In fact, if the float valve wore out, and allowed too much fuel into the float chamber, the fuel would start flowing into carb as soon as fuel pressure was applied, which would cause the fuel level to rise and fuel would flow uncontrollably thorough the carb jet into the intake manifold. The engine would usually stop running due to too rich a mixture.

I doubt very much Wonderboy has damaged piston rings, although improper break-in is not out of the question. You may have a fuel injector that's leaking after engine shutdown. Gas is pretty smelly stuff, so it doesn't take a lot to make the oil smell bad.

 

Excellent writeup about carburetors and direct fuel injection above.

Should add that there is also a (more common) type of fuel injection which injects (lower pressure) outside intake valve,
think that the just'aCooper would have this type.

Compression test should reveal ring seal and if you add some heavy oil to a 'low' cylinder it will increase compression reading, if rings are leaking.

A better test is when air is injected with piston at TDC (valves closed) and leakdown is meseaured.

My MA (who seemed knowledgable) told me that MINI Engine has a preliminary run-in and oil change at Factory.

I also know that my Cooper's oil looked clean at my 1250 mile change, but had a strong gasoline smell,
this had been true from back to the first dipstick oil level check and oil level never changed.

Now at 1,000 miles since oil/filter change and no gasoline smell in oil,
so I can assume that the rings are seated.

 

I had the same issue on both of the turbo cars I have owned. Something that needs to be considered here that has not be mentioned is your ring seal against the cylinder wall is not an air tight seal, it can't be and still have the piston freely move. Static, without the engine running, it is around a 2% leak. Once the piston is moving it can go up to 4% so if you figure 4% of the air your turbo is pumping out is mixing with fuel and then passing the rings into your crankcase it's highly likely there is a little bit of fuel in there. Like one poster mentioned it does not take a lot of gas to make something smell like gas. I got a few drops on my shoe the other day I smelled it all day long. I would not be overly concerned unless you are seeing smoke or the engine seems to be down on power or running a bit rough.

 

Thanks all and
Ken G/ Thanks for the good explanation.
pilotart/ I hope no gasoline smell once changed the engine oil.
Sweethouse1/ Yeah, I would not worry too much.