- Excessive blow-by: When the piston rings are worn or damaged, they can no longer seal the combustion chamber effectively, allowing excessive pressure and gases to escape into the crankcase. This pressure can cause oil to be forced up through the dipstick tube and out the dipstick hole.
- Clogged PCV valve: The PCV (positive crankcase ventilation) valve is responsible for regulating the flow of air and gases from the crankcase back into the intake manifold. If the PCV valve is clogged or malfunctioning, it can cause pressure to build up in the crankcase, leading to oil being forced out through the dipstick tube.
- Faulty piston rings: If the piston rings are worn, broken or damaged, they can no longer properly seal the combustion chamber. This can result in excessive blowby, causing pressure to build up in the crankcase and force oil out the dipstick tube.
- Oil overfill: If the engine oil is overfilled, it can cause the oil level to rise too high in the crankcase. This can lead to the oil being whipped up into a foam, which can then be forced through the dipstick tube by the pressure in the crankcase.
- Excessive turbocharger boost: If the turbocharger boost pressure is too high, it can cause excessive pressure in the crankcase, leading to oil being forced out the dipstick tube.
