Oil dilution is excessively rich fuel mixture or incomplete combustion that allows a certain amount of fuel to pass down between the pistons and cylinder walls and dilute the engine oil.
With that said, what makes an engine more prone to oil dilution?
It seems some engines are more prone to oil dilution than others. And an engine with a turbo is one of them.
What is it about turbo engines that makes them more prone to oil dilution?
Lastly, why do you think manufactures continue to sell cars with oil dilution problems, and why does it take so long to figure out how to solve for it?
Essentially it is caused by fuel getting past the piston rings. This is an issue for direct-injection turbo motors because most have a high pressure fuel pump which shoots fuel into the motor at a very high PSI. So high, you get fuel that gets past the rings and into the motor. As efficient as motors are now, they do not get hot enough to burn off that excess fuel. So it mixes with and 'dilutes' the oil. Hence, oil dilution.
Blowby is when pressure overcomes the piston rings. Turbos make pressure. Pretty straightforward.
So a regular engine usually won’t have it, because there is no added pressure?
Blowby can still happen on naturally aspirated engines. The combustion process creates tremendous pressures.
Blowby is more LIKELY on forced induction engines because obviously their purpose is to make the pressure greater.
The harder I squeeze a bottle, the harder I have to hold my thumb over the opening to contain the contents.
The amount of blowby also depends on the cylinder design, piston ring tension, oil lubrication, PCV regulation etc. Every engine has some amount of blowby, it's part of the reason we change the oil. Is there any particular reason you ask?
Thanks for the explanation.
I keep seeing posts about engines with oil dilution problems. So it got me to wondering about the root cause. And also wondering why manufacturers even with quality of Honda still some problems.
One would think they could catch oil dilution prívele me during the design and testing phase. But I gather it is harder to test for it. Either that, or they knowingly put oil dilution engines on the market.
I can't remember the title, but there was another topic about this... probably yours. @figmund-sreud explained that due to pressure from environmentalists, carmakers are making looser fitting pistons for lower emissions (which is retarded)
It may have been me. I asked a question about how regulations have impacted design/engineering.