A cold-hardening aluminum casting alloy with good thermal stability for the production of thermally and mechanically stressed cast components, wherein the alloy includesfrom 11.0 to 12.0 wt % siliconfrom 0.7 to 2.0 wt % magnesiumfrom 0.1 to 1 wt % manganeseless than or equal to 1 wt % ironless than or equal to 2 wt % copperless than or equal to 2 wt % nickelless than or equal to 1 wt % chromiumless than or equal to 1 wt % cobaltless than or equal to 2 wt % zincless than or equal to 0.25 wt % titanium40 ppm boronoptionally from 80 to 300 ppm strontiumand aluminium as the remainder with further elements and impurities due to production individually at most 0.05 wt %, in total at most 0.2 wt %. The alloy is suitable in particular for the production of cylinder crank cases by the die-casting method.