Quantified products (QP) collect data about themselves as a basis for data-driven services. They consist of fleets of physical products, IT components built into the products, IT services and business services. The product lifecycle management of QP has to integrate the individual lifecycles for the different components and faces the challenge of a large variability of possible customer solutions. Multi-aspect ontologies can serve as the fundament for an approach to capture interface specifications and formal dependencies of the different QP components and variants. Motivated by an industrial case study, the paper investigates the use of multi-aspect ontologies as support for QP engineering. The main contributions of this work are (1) an approach to integration of multi-aspect ontologies into QP engineering, (2) two industrial case studies showing the actual multi-aspect ontology, and (3) experiences from the case studies.