An improved hydroisomerization catalyst system and process for making a base oil product using a combined catalyst system comprising SSZ-91 molecular sieve and SSZ-95 molecular sieve. The catalyst system and process generally involves the use of a catalyst comprising an SSZ-91 molecular sieve and a separate catalyst comprising an SSZ-95 molecular sieve to produce dewaxed base oil products by sequentially contacting the catalysts with a hydrocarbon feedstock. The catalyst system and process provide improved base oil yield along with other beneficial base oil properties.