Oil Dilution

Sound like one or more of your local fuel suppliers is selling horribly low grade fuel that does not burn well enough to complete the combustion cycle so it stays liquid and gets pushed past the piston rings and into the oil.

Saw the same in my OLD diesel tractor a few years back. My diagnosis was that it's fuel getting past the piston rings, so had the tractor serviced and the problem went away.

For "petrol" cars that are not fuel injected, it may also relate to valve seals that are worn allowing fuel to enter the tappet/rocker cover and enter the crankcase oil there.

I'm not an engine person, so these are just "off the cuff" thoughts.

(Alternative reason, the differential in the tractor "makes" oil volume also unless it's used often and for long periods. That's water condensation inside the large castings, but you would have described "white" and frothy oil if water was the concern.

Hmm. Hope you don't take offense, but the word "automatically" is suspect to me. Most people these days do not check their oil levels themselves, they let the kid at the "Jiffy lube (or something like it)" check the oil.

How was this oil tested? Gasoline is a petroleum product, so is engine oil. How was the differentiation between petroleum and petroleum made?

It could be that that new kid is simply untrained, and is filling the oil to the point where it covers the word "full" on the dipstick, rather than to the line "full--->|" on the dipstick. Run a test. Take one of the cars that is showing this phenomenon (that you have control over - or can trust the owner to tell you who if anyone has done ANYTHING with it - preferably NOBODY but you), fill the oil yourself, then see if it happens again. If it does, then I would suspect that some damage has been done to the oil rings (blow-by of gas vapour into the crankcase), or to the valves and valve seals (again blow-by, but this time into the head, then draining back into the oil pan).

Blow-by of the oil rings can be caused by abrasives in the oil/ oil pan. Pull the pan and see if there is any sludge in the bottom. Oil filters will filter most things out, but if they get clogged, there is an oil filter bypass (basically a spring loaded disk) that will open up to allow flow. Blow-by of the valves/valve seals will be evident if you pull off the rocker cover and inspect the condition of the seals.

Good luck!

Hi

Thank you for your reply

The oil has been tested for viscosity at 40 degrees C and rated against the manufacturers specification. As you have mentioned that the guy at the filling station checks the oil and could have over filled the vehicle, i ruled that first. My own vehicle is showing the same results as well as 4 other vehicles who's oil i drained myself.

At this stage it seems to be linked to the fuel because all the cars tested are fuel injected and run on 95 octane fuel. I picked up this problem in a vehicle that had only 1936km on the clock which is basically brand new. The 4 vehicles that i took the follow up samples from had their oil drained, engine flushed with clean oil and oil filter changed. They started showing the same problem within 7 days (-/+ 500km)

Thank you

Where do you live (at least generally?)--the US, somewhere else?

Is there ethanol in the fuel?

I'm just wondering if something like ethanol in the fuel has done something to seals somewhere, or can bypass cylinder rings (in unburnt form) and get into the oil? Strictly wondering, have no knowledge or reason to believe that is a cause.

Ethanol boils at 173 F which is below the typical 180 F or higher engine operating temp so it would be naturally boiled out of the oil before it could ever build up.

I've seen this before, but it was with old style mechanical fuel pumps going bad. With the newer cars, there is only one way for fuel to get into the oil..........and that's through the rings.

This isn't even the biggest problem. The biggest problem is that gasoline isn't formulated to be a lubricant. Not only is there unnecessary wear and tear on the rings, cylinder walls and everything else, but this could also present a potential explosion hazard.

It could be that someone in town is diluting gasoline with something that doesn't burn very well, or their suppliers.

My 95 chev. suv had a worn out "spider" in the intake system that allowed full fuel pressure to slowly flood and force its way to the crankcase. I was lucky the engine did not explode.

I am not sure what your conditions are but severe dilution can happen with a lot of short trips in cold weather. Two things aggravate the situation: (1) combustion products blow by the rings - in theory this is mostly water vapor and gaseous carbon dioxide. The water vapor can condense to for liquid water if the crankcase never gets warm enough. This also promotes sludge formation. (2) another factor is that the fuel system runs very rich (excess fuel) after the engine has a cold start and only slowly transitions slowly to stoichiometric (idea fuel/air ratio, with no excess fuel) as the engine warms up. The warm-up strategy varies depending on the fuel system (carburator, port injection, or direct injection) - later strategies such a direct injection try to avoid rich operation modes. It is known that the automotive community that seen some gasoline-powered service trucks in Alaska have seen severe gasoline dilution in the oil / engine damage if they repeatedly idle for long periods (i.e. overnight) in bitterly cold weather (-40 F / -40 C). This is because they really struggle to keep the oil reasonably warm under this condition.

One of my uncles had a similar problem with a fuel injected Volvo 20+ years ago - the cause there was that the injectors were leaking after the engine was switched off - the leaking fuel found its way into the sump.

I cannot remember any more details - too long ago -

What causes fuel to get into the engine oil

This credible John Deere link mentions both low engine temperature (causing water, some gasoline build-up) and stale fuel (causing incomplete combustion for more gasoline-related problems). This supports what other have been saying.

Had this twice on cars with carbs. Stuck automatic choke, or thermostat removed so engine ran cold.

Once with fuel injection. Thermostat stuck open, so engine ran cold.

One more. Check the air filter. If clogged with oil from the sump breather pipe, it has the same effect as a stuck automatic choke.

I'd assume there is nothing terribly wrong with the cars. I'd work backwards and look for commons in the fueling. I would suspect with the limited information we have at this point that a fuel distributor (possibly one fueling station) is responsible. I'd ask the car owners for a history of where they usually buy fuel. I'd bet one name will keep popping up. Test that fuel for consistency. I bet you'll find your anomaly there.

With multiple cars doing it, including new ones, it sounds like there may have been a contaminent that caused damage to the rings. Pick a car from the group which would be easiest to check and have the rings looked at. If the rings are OK, the question becomes much more complex. If they are not OK, the type of damage my indicate what probably caused the problems, Bad fuel, somebody having fun and adding something to the fuel or oil chambers, or other sources.

Analyze the simplest causes first.

Do any of these vehicles have anything in common? Go to same gas station, same oil change facility, are they owned by the same family or company, been taken to the same repair facility for other problems?

Run a compression test on all suspect vehicles. If the test(s) indicate specified compression, you can rule out bad rings (but an excess of fuel after shutdown will still seep past good rings)

As far as stale or otherwise contaminated fuel, how do these vehicles perform at idle and while being driven? Good/bad?

I suspect a common denominator here.

Good day,

Analyze is what i did.

I live in a small town in the south of Namibia +- 7000 residents and i work for a Zinc producing mine. The mine is situated 31 km out of town. 75% of the vehicles tested drive out to the mine at least once a day. The minimum speed that the people travel at is 100km/h, this is for about 8km on the mines access road.

The other 25% of the vehicles travel in stop start situations in town only +- 10km per day. I took samples from them to rule out that it is a problem limited to vehicles that go out to the mine only. All vehicles tested are electronic fuel injected petrol vehicles and use the same 95 octane fuel. The town has only one filling station ( yes, that's how small it is)

At this stage my research also points to a problem with the fuel. Vehicles with carbs don't seem to be affected as much but they mostly run on a lower octane fuel. The fuel company sent a sample to their own lab and then told me that there is no contamination of their product ( as they would to cover them selves).

I have sent away diluted oil samples and a petrol sample to an independent lab in South Africa to be analyzed in detail. I posted on this site to help me get a better idea on what could be the cause, as the saying goes "two heads are better than one"

I hope this extra info can help you to get a better idea of the situation.

Thank you for all the replies

This is a fairly common occurrence for cars (engines) that never do any long runs. Only run cold....short drives.

It can even be that in some engines, also water/condensation gets into the lube oil and raises the level. It can be both fuel and water.....

The only fix I know of (assuming that the engine is in an otherwise good condition), is to go for a good 25 mile plus drive. At least once a month.....

But do keep an eye on the oil level as it can drop dramatically as the liquid(s) are boiled off.....and this could possibly cause engine damage. So take a few quarts of oil with "just in case!"

I am sure we have all driven behind a car where a liquid is pouring out of the exhaust, this is water from combustion, that came as steam out of the engine and condensed in a cold muffler.....as you burn Diesel/petrol, a lot of water is produced as the fuel burns....

This water combined with other exhaust products makes a weak acid and rots the muffler from the inside out. Less quickly with Diesel engines......

Very new and old worn engines will collect even more fluids in the oil.......

It seems its happening with many engines of different vehicles and different owners.....read original post for exact details......if I remember correctly, diesels and petrol engines mixed....

I somehow personally don't think that they can all have the same problem from the same defect.....or its highly unlikely......or I could be wrong.

I personally would simply guess that its only due to cold weather (winter) combined with short runs on all the vehicles concerned.....To the shops - stop - home - stop. Etc etc etc.....

Its certainly something that can affect almost any engine, most likely ones with no problems otherwise, no stored codes etc etc....assuming that the OP knows what he is talking about of course!!

Have a great day.

Hello Andy.Thanks for your reply.We all see or understand a little different.Makes life interesting.I will try and answer your post .#1.It seems its happening with many engines of different vehicles and different owners.....read original post for exact details......if I remember correctly, diesels and petrol engines mixed... From the OP,"I am finding more and more vehicles of different makes, models and driven km's that seen to allow fuel (gasoline/petrol to be precise ) to enter their engine oil".OK, i agree with different makes or models or if you prefer different vehicles and most likely different Owners.It does seem to me that he is limiting the problem to gasoline/petrol engines and not diesel.#2.I somehow personally don't think that they can all have the same problem from the same defect.....or its highly unlikely......or I could be wrong. From the OP,"At this stage it seems to be linked to the fuel because all the cars tested are fuel injected and run on 95 octane fuel.All vehicles tested are electronic fuel injected petrol vehicles and use the same 95 octane fuel. The town has only one filling station ( yes, that's how small it is)

At this stage my research also points to a problem with the fuel.Vehicles with carbs don't seem to be affected as much but they mostly run on a lower octane fuel". It seems to me that the OP is doing an excellent job narrowing down the possibilities to a point where i would take a Scientific Wild Ass Guess and say that it most likely is going to be the same problem from the same defect.#3.I personally would simply guess that its only due to cold weather (winter) combined with short runs on all the vehicles concerned.....To the shops - stop - home - stop. Etc etc etc..... From the OP,"I live in a small town in the south of Namibia +- 7000 residents and i work for a Zinc producing mine". A lttle Google search gave me>Namibia-Climate:desert;hot,dry,rainfall sparse and erratic.Ahhhhhh ? . #4.Its certainly something that can affect almost any engine, most likely ones with no problems otherwise, no stored codes etc etc....assuming that the OP knows what he is talking about of course!! From the OP,"Some were diluted by as much as 25%. Some owners drained almost double the amount of oil from the vehicle than what it was supposed to be" Double the Amount! I am calculating at least 3 if not 4 or 5 quarts of gasoline mixed with the oil.I cannot picture a modern gasoline engine's management system,(from the OP"I picked up this problem in a vehicle that had only 1936km on the clock which is basically brand new".) with that amount of gasoline in the oil not issuing trouble codes.However i am in the US,perhaps Namibia is different. To the OP Mr. Ockert."The fuel company sent a sample to their own lab and then told me that there is no contamination of their product".A Fuel Company saying that their fuel is not contaminated is not saying that the fuel is properly blended.From Wikipedia:"Overall, a typical gasoline is predominantly a mixture of paraffins (alkanes), naphthenes (cycloalkanes), and olefins (alkenes). The actual ratio depends on:

* the oil refinery that makes the gasoline, as not all refineries have the same set of processing units;
* crude oil feed used by the refinery;
* the grade of gasoline, in particular, the octane rating.

Currently, many countries set limits on gasoline aromatics in general, benzene in particular, and olefin (alkene) content. Such regulations led to increasing preference for high octane pure paraffin (alkane) components, such as alkylate, and is forcing refineries to add processing units to reduce benzene content.

Gasoline can also contain other organic compounds such as organic ethers (deliberately added), plus small levels of contaminants, in particular sulfur compounds such as disulfides and thiophenes. Some contaminants, in particular thiols and hydrogen sulfide, must be removed because they cause corrosion in engines. Sulfur compounds are usually removed by hydrotreating, yielding hydrogen sulfide, which can then be transformed into elemental sulfur via the Claus process."You may also be helped with an understanding of Reid Vapor Pressure,again Wikipedia:"Reid vapor pressure (RVP) is a common measure of the volatility of gasoline."Thank you for letting me share.

It sounds like you have badly worn piston rings to me!

Xanasax

If there's not white or blue smoke yet, the bore and rings are still OK.
I had a serious problem when a local fuel supplier added MTBE to low octane fuel to increase its octane rating. Caused brown deposits on sparkplugs and accelerated engine wear. When the engine was stripped (only 80 000kM), there was severe piston, rings and upper bore wear. The bore looked as though it had rusted. There was never coolant leakage or cold running.
See: http://auto.howstuffworks.com/fuel-efficiency/fuel-consumption/question347.htm

Also MTBE poisons catalytic converters. Unless you choose to "Gut the cat", it's very expensive to replace!

That sucks! Especially if, as I understand, MTBE additions are mandated by the government (in some states?) during certain parts of the year?

I think your worries are unfounded, you have some other problems with your Cats and engine. Look here:-

http://en.wikipedia.org/wiki/MTBE

Its been in use since 1979, mainly to replace the lead content FOR catalytic converters!!!!

Its not a "nice" chemical, but many are far worse......

It is slowly being phased out in many areas because of its affect on water supplies....

If it had the effects on engines that you claim, it would have "killed" many engines and cats all over.....

I personally find cheap oils to be far worse for engines than any fuel that achieves the DIN standard (which is why I use the best oils there are available today, LL3).

It has long been normal in the USA for many people to use technically very old fashioned engine oils and replace them at quite low mileages.

I drive a VW Diesel engine (in a Mitsubishi) and with the LL3 oil, I can drive between 30 and 40,000 Kms between changes. The computer tells me when its required. Furthermore, the engines run in VERY slowly (shows good lubrication/low wear!), For example, I have found (with 5 cars, over 14 years with these engines) that TDI motors from VW need at least 120,000 Kms to achieve the lowest oil consumption of all (one top up in the 30,000 Kms), but slowly reduce the consumption even further.

Which is why I say that these engines with 120,000 kms are just "run in"!

This remains then the same as long as I have ever had an engine......Although I have never had any car longer than 150,000 with VW engines, I know a taxi company in Vienna that sells their Skodas with the same engines at between 500 - 600,000 kms, still running as normal.......they achieve that mileage in only 2 years (24 x 7 taxi usage!).

I don't know if you are using the older style engine oils or not, it will be very interesting to hear from you on that subject!!

I just cannot believe that this chemical is the reason for your problems...

Have a great day.....

If you ran straight mineral oil for the first 1000km (500 Miles), you could bed down the rings more quickly and get high fuel efficiency and low oil consumption earlier.

However the manufacturer may have machined the bores, rings and journals to such a fine degree that the bedding down is almost a given when the vehicle is first driven. So follow the maker's instructions for oil and changes.

If you ever get a problem in a TDI motor, they test the oil and if the wrong oil is found (tiny traces) your guarantee is gone immediately, on the motor at least. Its not worth the risk....

The oil consumption, although high in the first 10,000 KMs, for example you will need 2.5 liters extra, tails off quickly after that, but goes on improving till around 120,000 kms..

Nobody is willing to suggest vandalism?

I'm in the camp that says greed. Nothing like diluting fuel to increase profit.

A very easy way to check for excessive blow-by that allow enough fuel into the crankcase to dilute the oil can be easily checked by removing the oil fill with the engine idling. If the rings are damaged then you will have a large amount of vapor blowing out of the filler cap opening. If the vehicles are of fairly rent manufacture then the ethanol in the fuel should not affect the rubber type seals on the valve stem seals as most of them are of Viton composition and can withstand the ethanol. If you notice that there is a lot of blow-by I would run a compression check on the cylinders and see if one of them or multiple cyls. have low compression. That will tell you which way to go next which would be a physical exam of the cylinders to see if there is sever scouring on the walls, if so then I would look at the oil for some type of abrasive contaminant in the oil.

The one fuel grade and one service station makes it sound like it was a problem with one delivery of fuel. what is the turn over for fuel at the servicre station? Are there people who use that fuel grade who do not have the problem? You might be able to correlate a time when none of them got fuel. Again physically looking at the rings and pistons of one of the vehicles might give you a cause. Another question, do the vehicles appear to have less power?

How many other FI cars use the same fuel without problems?

IE what percentage of cars show this problem - then what is different about them - usage?

other additives the owners may have added?

anything else that may have been done differently from those not exhibiting the problem?

If you open the "oil" filler cap and look inside the "710" space,

Water: looks like mayonnaise inside. Petrol, you'll get the smell.
It's more than likely this problem is caused by an undesirable additive to the fuel.

White smoke: Coolant leakage or cold running. Short trips daily, with condensation in exhaust system.

Blue smoke: Burning oil because of worn engine and rings.

Black smoke: Over rich fuel air mixture.

I've had VW's and Ope'ls. Also two Fiat's. An 850 Special and an Uno.. Did 7500km trips around Namibia flat out and had no problems. Added 500ml on the way back home, at Van Rhynsdorp. All cars did more than 140 000km before selling them. As mentioned above, check the fuel pump diaphragm, then find out if someone is adding "soap" to the local fuel! Some used oil at first, but all settled down by 50 000km.