In a current project, OWI Science4Fuels gGmbH and the Institute of Plastics Processing are investigating the compatibility of paraffinic fuels with plastics commonly used for tanks and fuel-carrying fittings of oil heating systems. In particular, the focus is on the effect in existing consumption plants for heating oil. The interaction with the tank materials polyethylene (PE) and polyamide (PA), with protective film made of polyvinyl chloride (PVC), with seals made of elastomers and with other polymers used in fittings is investigated.