High fuel content in engine oil
07-01-2014, 06:11 AM
#1
Advanced
Thread Starter
High fuel content in engine oil
Hi all,
Since last year I decided to start doing oil analysis of the oil of my TT. The results concern me somewhat since it's been between 2.2% and 2.6% of fuel in the oil.
The lab report says it's too high and that it degrades the lubricating capabilities of the oil which is true, but I have no reference values for 996 Turbos, meaning I don't know what is normal and is not. The lab doesn't know either.
Considering the engine configuration (boxer) it is to be expected both a higher fuel content in the oil and a higher oil consumption than in vertical cylinder engines, however, I don't know and can't find any references on this. The dealer also has no idea.
So: does anyone know anything about this? Are there other experiences of oil sampling in the forum?
Since last year I decided to start doing oil analysis of the oil of my TT. The results concern me somewhat since it's been between 2.2% and 2.6% of fuel in the oil.
The lab report says it's too high and that it degrades the lubricating capabilities of the oil which is true, but I have no reference values for 996 Turbos, meaning I don't know what is normal and is not. The lab doesn't know either.
Considering the engine configuration (boxer) it is to be expected both a higher fuel content in the oil and a higher oil consumption than in vertical cylinder engines, however, I don't know and can't find any references on this. The dealer also has no idea.
So: does anyone know anything about this? Are there other experiences of oil sampling in the forum?
07-01-2014, 01:27 PM
#2
According to my report from Blackstone Lab, the fuel content should be less than 2.0%
Do another oil sample after your next oil change. Remember to let some oil drain out before taking a sample.
Do another oil sample after your next oil change. Remember to let some oil drain out before taking a sample.
07-01-2014, 06:49 PM
#4
Race Director
The Turbo engine is of course turbo-charged and turbo-charged engines experience more blow by than N/A engines. Thus turbo-charged engines generally have more combustion by-products in their oil than another otherwise identical N/A engine.
However, I'm not sure where your oil's fuel content fits in the fuel content of the set of turbo-charged engines.
You have to be careful about how you obtain the oil sample to analyze. If the engine is not hot and sits too long the oil will stratify and if you take a sample from the wrong place or at the wrong time you do not get a sample of oil that is representative of the oil overall.
The best way to get a sample is to with the engine warmed up and shortly after shutting it off draining the oil and capturing a sample from mid-stream. You want to avoid the oil that comes out initially and you want to avoid the oil that comes out last.
Even if the fuel content is high it could be nothing more than you just do not drive the car enough for the engine to get hot enough for the fuel to boil out. However, I have to point out the I'm sure obvious to you that fuel boils before water so if the oil had a goodly amount of fuel in it its water content should be up to. Do you have the water content?
You can look at the fuel trims, both short term and long term, and see if you can observe one bank running a bit lean. This can be from a leaking injector which makes the bank run rich and to compensate for this the DME will lean the bank out. It can't go very far though or the cylinders with the good injectors will run too lean and misfire.
The absence of misfires suggests then the leaking injector, if there is one, only leaks (dribbles) a bit of fuel after you shut off the engine. It is not bad enough to noticeably affect fueling when the engine is running.
Assuming then an injector is at fault, you may be able to address this by running a bottle or two of Techron as per directions on the bottle label to clean the fuel system and remove any deposits from the injectors with the hope that the injector is leaking due to a bit of debris that Techron will help dissolve or loosen and flush through.
But be sure of the oil sampling results first. You may have just given your engine a self-inflicted imaginary fuel in the oil problem by taking a bad sample of oil.
However, I'm not sure where your oil's fuel content fits in the fuel content of the set of turbo-charged engines.
You have to be careful about how you obtain the oil sample to analyze. If the engine is not hot and sits too long the oil will stratify and if you take a sample from the wrong place or at the wrong time you do not get a sample of oil that is representative of the oil overall.
The best way to get a sample is to with the engine warmed up and shortly after shutting it off draining the oil and capturing a sample from mid-stream. You want to avoid the oil that comes out initially and you want to avoid the oil that comes out last.
Even if the fuel content is high it could be nothing more than you just do not drive the car enough for the engine to get hot enough for the fuel to boil out. However, I have to point out the I'm sure obvious to you that fuel boils before water so if the oil had a goodly amount of fuel in it its water content should be up to. Do you have the water content?
You can look at the fuel trims, both short term and long term, and see if you can observe one bank running a bit lean. This can be from a leaking injector which makes the bank run rich and to compensate for this the DME will lean the bank out. It can't go very far though or the cylinders with the good injectors will run too lean and misfire.
The absence of misfires suggests then the leaking injector, if there is one, only leaks (dribbles) a bit of fuel after you shut off the engine. It is not bad enough to noticeably affect fueling when the engine is running.
Assuming then an injector is at fault, you may be able to address this by running a bottle or two of Techron as per directions on the bottle label to clean the fuel system and remove any deposits from the injectors with the hope that the injector is leaking due to a bit of debris that Techron will help dissolve or loosen and flush through.
But be sure of the oil sampling results first. You may have just given your engine a self-inflicted imaginary fuel in the oil problem by taking a bad sample of oil.
07-02-2014, 06:14 PM
#5
Advanced
Thread Starter
Thanks for your comments.
The car starts just fine and cranks normally. There's no excessive smoke starting and none while working. Durametric reports no errors and no misfires.
I'm wondering about all this because it's the 2nd year in a row with high fuel content (no water or glycol in the sample)
I haven't watched the oil sampling procedure which does concern me a bit. I fear the mechanics simply let the oil flow into a pan/tray that may be washed with leftover gas and then taken the sample. They say they didn't but...
10000km from now I'll sample the oil myself or be there to witness it, the only way to be sure.
The car starts just fine and cranks normally. There's no excessive smoke starting and none while working. Durametric reports no errors and no misfires.
I'm wondering about all this because it's the 2nd year in a row with high fuel content (no water or glycol in the sample)
I haven't watched the oil sampling procedure which does concern me a bit. I fear the mechanics simply let the oil flow into a pan/tray that may be washed with leftover gas and then taken the sample. They say they didn't but...
10000km from now I'll sample the oil myself or be there to witness it, the only way to be sure.