Why are turbos more likely to burn oil?

Turbocharged engines are more likely to burn oil due to several factors related to the high heat and pressure conditions that turbos operate under. Here are the main reasons:

1. Increased Heat and Pressure

• High Temperatures: Turbochargers work by forcing more air into the engine, which increases combustion temperatures. The turbo itself spins at extremely high speeds (up to 200,000 RPM), creating additional heat. The oil that lubricates and cools the turbo can break down at these elevated temperatures, which may lead to oil burning.
• High Pressure: The turbo operates under higher pressure, which can force oil through seals and gaskets more easily. When oil leaks into the combustion chamber or exhaust system, it burns, causing visible smoke and oil consumption.

2. Turbo Seals Wear

• Turbo Seals: The seals in a turbocharger are designed to keep oil contained while allowing high-speed rotation of the turbine and compressor. Over time, these seals can wear out or degrade due to the extreme conditions they operate under, allowing oil to leak into the intake or exhaust systems, where it can be burned.
• Positive Crankcase Pressure: The turbocharger increases pressure within the engine, particularly in the crankcase. If this pressure becomes too high, it can push oil past the seals into the intake manifold, contributing to oil burning.

3. Oil Drainage Issues

• Oil Drainage: Turbochargers rely on proper oil flow to stay lubricated and cooled. If the oil return path from the turbo to the oil pan becomes restricted (due to sludge buildup, poor maintenance, or improper design), oil can back up into the turbo and get burned.
• Improper Oil Levels: Insufficient or excessive oil levels can cause drainage issues, which may lead to the turbo drawing oil into the combustion chamber.

4. Oil Contamination

• Oil Breakdown: The higher operating temperatures in turbocharged engines can lead to faster degradation of engine oil, especially if the oil isn't formulated for high heat resistance. Once the oil starts to degrade, it loses its lubricating properties, increasing the likelihood of burning.
• Sludge Formation: Heat and contaminants can lead to oil sludge formation, which can block oil return lines or cause oil to get trapped in the turbo, leading to increased oil consumption and burning.

5. Boost Pressure and Blow-by

• Boost Pressure: Turbochargers increase boost pressure inside the engine, which can exacerbate "blow-by" (when combustion gases escape past the piston rings into the crankcase). This pressure can push oil into the intake system or the combustion chamber, where it gets burned.
• Increased Blow-by: Under boost, the higher cylinder pressures can lead to more blow-by, which increases crankcase pressure and forces oil vapor into the intake system through the PCV (positive crankcase ventilation) valve, contributing to oil consumption.

6. Poor Maintenance

• Oil Quality: Using lower-quality oil that isn't rated for turbocharged engines can result in quicker oil breakdown and increased burning. Turbo engines typically require synthetic oil due to its ability to withstand higher temperatures.
• Lack of Regular Oil Changes: Failing to change the oil at recommended intervals can lead to sludge buildup, increased wear on turbo seals, and contamination, all of which increase the likelihood of burning oil.

Conclusion

Turbocharged engines are more prone to burning oil due to the high temperatures and pressures they generate, the potential for turbo seal wear, oil drainage issues, and the increased risk of oil contamination or breakdown. Regular maintenance, using the correct oil, and ensuring proper turbo lubrication and cooling are essential to minimize oil burning in turbocharged engines.