We consider the steady flow of five commonly encountered hydrocarbons in their dense gas regime. Isentropic flows are first examined and it is shown that dense gas effects lead to a non-monotone variation of the Mach number with density. It is also demonstrated that these effects may give rise to an increase, rather than the classical decrease, in the Mach number across oblique compression shocks. Significant increases in the shock detachment angle are also reported.