  We present here, for the first time, a 2D study of the overshoot convective
mechanism in nova outbursts for a wide range of possible compositions of the
layer underlying the accreted envelope. Previous surveys studied this mechanism
only for solar composition matter accreted on top of carbon oxygen (C-O) white
dwarfs. Since, during the runaway, mixing with carbon enhances the hydrogen
burning rates dramatically, one should question whether significant enrichment
of the ejecta is possible also for other underlying compositions (He, O, Ne,
Mg), predicted by stellar evolution models. We simulated several non-carbon
cases and found significant amounts of those underlying materials in the
ejected hydrogen layer. Despite large differences in rates, time scales and
energetics between the cases, our results show that the convective dredge up
mechanism predicts significant enrichment in all our non-carbon cases,
including helium enrichment in recurrent novae. The results are consistent with
observations.
