An improved hydroisomerization catalyst and process for making a base oil product using a catalyst comprising SSZ-91 molecular sieve and ZSM-12 molecular sieve. The catalyst and process generally involves the use of a catalyst comprising an SSZ-91 molecular sieve combined with a ZSM-12 molecular sieve to produce dewaxed base oil products by contacting the catalyst with a hydrocarbon feedstock. The catalyst and process provide improved base oil cold properties, such as pour point and cloud point, along with other beneficial base oil properties.