Check the condition of your Porsche's AOS with the CR Tools Crankcase AOS Vacuum Measurement Manometer Tool. Measures crankcase vacuum to diagnose possible false air leaks (low vacuum), AOS air oil separator failure (high vacuum), and evaluate overall engine health (ring sealing). Developed by Tony Callas and manufactured by Callas-Rennsport. Kit includes adapters for most modern (watercooled) Porsche models as well as specifications for normal crankcase vacuum levels for most models. Learn More