Due to the global drive for carbon neutrality, passenger vehicle gasoline engines are transitioning to higher levels of electrification, such as hybrid electric vehicles and plug-in hybrid electric vehicles, HEVs and PHEVs. Compared with conventional internal combustion, ICE only operation, the combustion engine in a HEV or PHEV typically operates for shorter periods. In turn the engine coolant and lubricant temperatures are often lower. Such cooler engine running is particularly noticeable for a variety of conditions including short journeys in charge-sustaining mode, urban motoring, a journey length towards the end of the electric range, at cold ambient temperatures, or a combination of these conditions. All C-type piston rings allow limited combustion gases to escape through the ring end-gap. Though the crankcase ventilation system will remove the blowby gases into the engine air inlet system, the crankcase blowby gases are able to mix with the lubricating oil as it returns to the sump. However, the ability of fuel and water in the blowby to evaporate from the engine oil is influenced by temperature. This paper presents sensor data showing, in real time, how this water exists in the blowby gases within the airspace of the engine crankcase. With direct reading sensors it shows how the water level in the oil increases and decreases in key areas within a running engine over the WLTC drive-cycle. Data for a standard internal combustion engine is compared with a plug-in hybrid cycle, in charge-sustaining mode. A range of lubricant formulations are tested. A comparison is established, between the observed water content sensor data over a single cycle with the widely known Karl Fischer titration method over a longer run test. Aspects of Karl Fischer titration sample practical preparation are discussed, these are required for a used oil sample with high water content.
