Composite materials are used in several engineering applications, where can be exposed to a range of corrosive environments during their in-service life. Thus, it is necessary understanding the impact of a corrosive environment in the working life of composite. According the authors’ knowledge, the effect of different commercial oils was not yet studied. Therefore, glass fibre/epoxy composites were subjected to oil immersion tests, using an universal multi-grade engine oil (15W-40) and an extra high performance hydraulic brake fluid (DOT 4), in order to study the effects of oil absorption behaviour on flexural and impact strength properties of glass fibre/epoxy composites. Both solutions affect the flexural properties and the impact strength. However, for all tests performed, the automotive brake fluid promotes the lowest values comparatively to the automotive engine oil.