That's right, WD40 can affect some O rings, as it's made up of petrol distillates, amongst other stuff, and can cause them to swell. We recently had problems with some components at work, and I spoke to the technical guys at WD's head office and our O ring supplier, the consensus was to either change the O ring material to Viton (the green coloured ones used in carbs. etc.) or use a silicone based lubricant instead. |