o by 0.5... The 23.0 original ratio allows for easier cold weather starting= . I think if you always use a block heater and your winters are not too sev= ere, then this is a viable option. One poster states that 18.0 will yield t= he best Diesel performance, maybe VW should employ SAAB technology and use = a veriable compression ratio.... just a one penny thought by Adrian the mad= man --