Methods are provided for using a molecular sieve catalyst for dewaxing formed using a synthesis mixture comprising a morphology modifier. The catalyst may be used, for example, for production of a lubricant base stock. For example, ZSM-48 crystals formed using the morphology modifier (and/or formulated catalysts made using such crystals) can have an increased activity and/or can provide an improved yield during catalytic dewaxing of lubricant base stocks.