Yes. Aluminum in particular is a fairly unstable material. You can anodize the heck out of it but eventually Entropy takes over. Add harsh chemicals such as say Oxygen and the process speeds up. Same thing for plated steel parts, exposure to oxidants takes its toll. The only way to know whats actually in that 'pump gas' is to pay to have it tested yourself. But don't publish the results or Big Oil will come after you. Alcohols can be aggressive, that's why they make more power.