With wear values that good, I wonder if a dismal point was moved mistakenly. 0.5 instead of 5.0?
Fuel dilution causes
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Originally Posted By: Eddie
With wear values that good, I wonder if a dismal point was moved mistakenly. 0.5 instead of 5.0?
Polaris says they flagged the high fuel and retested to be sure. Plus, Polaris uses gas chromatography to gauge fuel dilution instead of inferring a value based on flashpoint like Blackstone, which should give a much more accurate result. I had a Blackstine UOA on this car earlier: wear metals and viscosity were very similar but Blackstone estimated fuel dilution at 1% instead of 5%. It's all very puzzling.
With wear values that good, I wonder if a dismal point was moved mistakenly. 0.5 instead of 5.0?
Polaris says they flagged the high fuel and retested to be sure. Plus, Polaris uses gas chromatography to gauge fuel dilution instead of inferring a value based on flashpoint like Blackstone, which should give a much more accurate result. I had a Blackstine UOA on this car earlier: wear metals and viscosity were very similar but Blackstone estimated fuel dilution at 1% instead of 5%. It's all very puzzling.
Originally Posted By: Ram01
Fuel dilution causes timing chain wear . I would step up to a 5w30 syn oil .
Timing chain wear??? I would be more concerned with bearing wear. Your statement makes no sense, I doubt a synthetic will solve lubrication issues brought on by fuel dillution.
Fuel dilution causes timing chain wear . I would step up to a 5w30 syn oil .
Timing chain wear??? I would be more concerned with bearing wear. Your statement makes no sense, I doubt a synthetic will solve lubrication issues brought on by fuel dillution.
Originally Posted By: Lubener
Originally Posted By: Ram01
Fuel dilution causes timing chain wear . I would step up to a 5w30 syn oil .
Timing chain wear??? I would be more concerned with bearing wear. Your statement makes no sense, I doubt a synthetic will solve lubrication issues brought on by fuel dillution.
Aside from the concerns about just the timing chain, Ram01 statement makes perfect sense. Fuel dilution means viscosity loss, which in turn increases the time the components operate in the boundary condition instead of full hydrodynamic mode. Bumping up the viscosity of the oil ensures more time in the hydrodynamic range and less in the boundary.
Originally Posted By: Ram01
Fuel dilution causes timing chain wear . I would step up to a 5w30 syn oil .
Timing chain wear??? I would be more concerned with bearing wear. Your statement makes no sense, I doubt a synthetic will solve lubrication issues brought on by fuel dillution.
Aside from the concerns about just the timing chain, Ram01 statement makes perfect sense. Fuel dilution means viscosity loss, which in turn increases the time the components operate in the boundary condition instead of full hydrodynamic mode. Bumping up the viscosity of the oil ensures more time in the hydrodynamic range and less in the boundary.
Why is GDI worse for fuel dilution? I thought it kept fuel closer to the center of the chamber, and since it burns so clean, there should be less raw fuel, no? I know port fuel injection was aimed at the plug but still, I'd thought (part of) the point was to keep air/fuel from those pesky ring lands.
Don't recall diesels having a fuel dilution problem... soot yes, fuel no.
Don't recall diesels having a fuel dilution problem... soot yes, fuel no.
Originally Posted By: supton
Why is GDI worse for fuel dilution? I thought it kept fuel closer to the center of the chamber, and since it burns so clean, there should be less raw fuel, no? I know port fuel injection was aimed at the plug but still, I'd thought (part of) the point was to keep air/fuel from those pesky ring lands.
Don't recall diesels having a fuel dilution problem... soot yes, fuel no.
That's because the shape of the piston head is totally different than in gas engines and diesels do not require a separate ignition source, so the injector can sit right at TDC, where the sparkplug would normally sit in gasoline engine. It gives a nice and uniform spray pattern into the combustion chamber. The injectors spray diesel fuel directly into the small chamber that is made in the piston, usually close to when the piston is at TDC and the mixture self ignites. The fuel has little chance of touching the cylinder walls.
In gasoline engines, the fuel is sprayed into the combustion chamber so that it can mix with air and the injector has to be at an angle and off center, because the sparkplug must be seated right at TDC. Since fuel injectors are pretty bad at atomizing fuel, when compared to carburetors, and in DI fuel is directly sprayed into the combustion chamber at high pressures, that spraying action washes off the cylinders and some fuel ends up making it past the rings.
With port injection, the fuel at least has more time to be mixed with air as it makes its way past the intake valve, which usually creates a swirling action as well, plus much less pressure, hence much less fuel dilution.
Why is GDI worse for fuel dilution? I thought it kept fuel closer to the center of the chamber, and since it burns so clean, there should be less raw fuel, no? I know port fuel injection was aimed at the plug but still, I'd thought (part of) the point was to keep air/fuel from those pesky ring lands.
Don't recall diesels having a fuel dilution problem... soot yes, fuel no.
That's because the shape of the piston head is totally different than in gas engines and diesels do not require a separate ignition source, so the injector can sit right at TDC, where the sparkplug would normally sit in gasoline engine. It gives a nice and uniform spray pattern into the combustion chamber. The injectors spray diesel fuel directly into the small chamber that is made in the piston, usually close to when the piston is at TDC and the mixture self ignites. The fuel has little chance of touching the cylinder walls.
In gasoline engines, the fuel is sprayed into the combustion chamber so that it can mix with air and the injector has to be at an angle and off center, because the sparkplug must be seated right at TDC. Since fuel injectors are pretty bad at atomizing fuel, when compared to carburetors, and in DI fuel is directly sprayed into the combustion chamber at high pressures, that spraying action washes off the cylinders and some fuel ends up making it past the rings.
With port injection, the fuel at least has more time to be mixed with air as it makes its way past the intake valve, which usually creates a swirling action as well, plus much less pressure, hence much less fuel dilution.
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Originally Posted By: supton
Why is GDI worse for fuel dilution? I thought it kept fuel closer to the center of the chamber, and since it burns so clean, there should be less raw fuel, no? I know port fuel injection was aimed at the plug but still, I'd thought (part of) the point was to keep air/fuel from those pesky ring lands.
Don't recall diesels having a fuel dilution problem... soot yes, fuel no.
It is driven by compression ratios. DIs tend to have higher compression ratios. This increases detonation/knock. In order to combat this they have to lower the combustion chamber temperature OR increase the octane rating. In order to allow 87 octane usage, they choose to enrich the air to fuel ratio. The extra fuel cools the combustion chamber preventing knock/detonation but the super rich ratio results in a lot of unburned fuel getting into the oil.
Why is GDI worse for fuel dilution? I thought it kept fuel closer to the center of the chamber, and since it burns so clean, there should be less raw fuel, no? I know port fuel injection was aimed at the plug but still, I'd thought (part of) the point was to keep air/fuel from those pesky ring lands.
Don't recall diesels having a fuel dilution problem... soot yes, fuel no.
It is driven by compression ratios. DIs tend to have higher compression ratios. This increases detonation/knock. In order to combat this they have to lower the combustion chamber temperature OR increase the octane rating. In order to allow 87 octane usage, they choose to enrich the air to fuel ratio. The extra fuel cools the combustion chamber preventing knock/detonation but the super rich ratio results in a lot of unburned fuel getting into the oil.
Feel free to correct me if I'm wrong, but reading here it seems Polaris UOAs tend to show more high fuel percent alerts/flags than Blackstone UOAs. I understand this is DI too, which will show more fuel dilution. I don't know how many miles on the CRV, but I wouldn't panic just yet. I'd give it more time to settle down and perhaps try Blackstone next time for the UOA.
Originally Posted By: Sayjac
Feel free to correct me if I'm wrong, but reading here it seems Polaris UOAs tend to show more high fuel percent alerts/flags than Blackstone UOAs. I understand this is DI too, which will show more fuel dilution. I don't know how many miles on the CRV, but I wouldn't panic just yet. I'd give it more time to settle down and perhaps try Blackstone next time for the UOA.
12,000 miles and not ready to panic. As to Blackstone vs. Polaris, I believe Blackstone infers a fuel dilution % by human observation of flashpoint as a sample is heated. So there are two variables: the human observation and the attempt to translate this imperfect measure into a dilution %. Polaris uses gas chromatography, which afaik has no human intervention and no subjectivity. I suppose Polaris' machinery could be mis-calibrated, but it seems to me the Polaris method is lots more credible.
As I mentioned in a different thread, I've had two separate samples taken on two different OCIs, one by Blackstone and one by Polaris. Mileage and driving conditions were similar for each sample. Blackstone reported 1% dilution and viscosity of 6.5, Polaris 5% dilution and viscosity of 6.5. So both samples reflect substantial shearing but very different dilution. I'd rather believe Blackstone but not sure the low dilution lines up with the reduced viscosity.
Feel free to correct me if I'm wrong, but reading here it seems Polaris UOAs tend to show more high fuel percent alerts/flags than Blackstone UOAs. I understand this is DI too, which will show more fuel dilution. I don't know how many miles on the CRV, but I wouldn't panic just yet. I'd give it more time to settle down and perhaps try Blackstone next time for the UOA.
12,000 miles and not ready to panic. As to Blackstone vs. Polaris, I believe Blackstone infers a fuel dilution % by human observation of flashpoint as a sample is heated. So there are two variables: the human observation and the attempt to translate this imperfect measure into a dilution %. Polaris uses gas chromatography, which afaik has no human intervention and no subjectivity. I suppose Polaris' machinery could be mis-calibrated, but it seems to me the Polaris method is lots more credible.
As I mentioned in a different thread, I've had two separate samples taken on two different OCIs, one by Blackstone and one by Polaris. Mileage and driving conditions were similar for each sample. Blackstone reported 1% dilution and viscosity of 6.5, Polaris 5% dilution and viscosity of 6.5. So both samples reflect substantial shearing but very different dilution. I'd rather believe Blackstone but not sure the low dilution lines up with the reduced viscosity.
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