Viton and nitrile are what's used for injector O-rings. Both materials are very resistant to hydrocarbons. I've been using a drop of gas as lube on injector O-rings. Any elastomer doesn't slide well and resists plastic deformation. Without lube the seal may not pop in place. The lube also prevents the O-ring from getting scuffed during installation. The lube serves only as installation lube. Engine oil should be fine also.
