Oil Consumption & Volatility Explained

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Ever torn down a motor and seen oil in the intake manifold? How about an intake valve dirtier than an exhaust valve? Ever wondered how that happened?

The one word answer is Volatility. This fancy sounding word basically means how much vapor a motor oil releases when it gets hot. You know how water vapors rise off a pot of water before it begins to boil? The same thing happens to you motor oil inside your engine. As oil splashes onto the pistons and valve springs to keep them cool, the high temperature causes some of the oil to evaporate.

So what does this have to do with oil in the intake? Well, modern engines have a Positive Crankcase Ventilation valve that vents these oil vapors into the intake manifold. These oil vapors now condensate in the cool air/fuel mixture, which leaves the oily deposits in the intake manifold and on the intake valve.

Check out the new 2014 Corvette engine. Since this engine is direct injected, there is no fuel to wash the oil down the intake manifold and to help prevent excessive intake valve deposits. So what did GM do? They installed an oil separator in the PCV line that condensates the oil and drains it back into the engine before it gets into the intake stream.

So if you don’t have a 2014 Corvette, what can you do? For starters, using a lower-volatility motor oil is the first line of defense. Simply put, the fewer the oil vapors, that much less oil gets into the PCV system in the first place. The result is more oil kept in the crankcase where it belongs. The second thing you can do is install an aftermarket PCV line oil catch can.

These two steps will reduce the amount of oil getting into the intake tract. Obviously a cleaner intake valve will flow more air for better power and fuel economy. These steps also reduce oil consumption, which helps to protect O2 sensors and catalytic converters from damage due to excessive oil consumption.

The key is using low-volatility base oils in the motor oil formula. Conventional refined crude base oil has volatilities in the range of 20 to 30% for a typical viscosity motor oil. A traditional synthetic base oil drops that volatility down to 14%, but even newer synthetic base oils drop the volatility down to an incredible 5%. Unfortunately for the OEM car companies, the supply of these ultra low-volatility oils is limited, so while they are a technical solution, they are not a practical one on a global scale. Fortunately for the enthusiast market, supply of the ultra low-volatility base oil is sufficient to cover the needs of the high performance crowd.

This ready supply enables specialty oils like Driven LS30 and FR20 to reduce oil consumption AND contain more ZDDP for better engine protection. The O2 sensors and catalytic converters don’t know how much ZDDP is in the motor oil because it stays where it should be – in the crankcase lubricating your engine. LS30 can contain 50% more ZDDP since the volatility is 67% less than standard base oils. The higher quality base oil delivers better all-around protection and performance.