To distribute oil derivatives by multi-product pipelines is an important problem faced by the petroleum industry. Some researchers deal with it as a discrete problem where batches of products flow in a network. Usually, no separation devices exist between batches of different products and losses due to interface can be significant. Minimizing delivery time is a usual objective handled by engineers when scheduling products in pipeline networks. Nevertheless, costs due to interface cannot be disregarded. This paper addresses the problem where these two criteria are considered simultaneously. A Transgenetic Algorithm is proposed for it and applied to 30 real-like instances. Transgenetic algorithms are evolutionary approaches based on interactions between a host and its endosymbionts. Computational experiments show that the proposed approach is very effective when compared to other algorithms proposed previously in literature.