Can anyone tell me Please? I have a bottle of redx would it harm the lawnmower engine if I put a drop of it in with the petrol. I think its a few years old or will I be best of not putting it in. or has engine’s moved on from year’s ago and do not need a clean out also I remember year’s a go Castrol had a oil out named Castrol R was it the same as redX or not.