lead-free and unleaded

[Goldie]

What is the difference between 'lead-free' petrol and 'unleaded' petrol? Or are they the same thing?

[sft42]

Both are the same thing.....Unleaded is a better term than lead free as some people seem to be under the impression that petrol had lead in it all the time......Petrol is a simple Hydrocardon and apart from some added detergents and other trace chemicals used to prevent "pinking" or knocking in the engine that is all it is......Lead used to be used previously for that very purpose until it's dangers were discovered.

[carlos]

I used to work in a Petrol Station(but that doesn't make me an expert I know!). It was a long time ago but if I remember correctly Lead Free petrol replaced the old 4* - It is actually Lead Replacement Petrol (LRP) and it's got an additive to replace the lead. Unleaded never had any lead in it to begin with so although neither contains lead they are chemically different hence one needing lead or a substitute, and the other not. Aren't they phasing LRP out?.....Just before I left the station they drained the LRP tank, and turned it into an Unleaded tank. I think that a few stations will still hold LRP as a lot of classic cars won't run on Unleaded. My appologies if i'm wrong, but I think thats how it is.

[carlos]

My appologies.....I was still two-finger typing my answer and it took me a while! My answer wasn't contradicting sft42 - I didn't see it until I'd posted.

[carlos]

If Lead was put into petrol to improve the octane rating, does this mean that Unleaded has a lower otane rating than LRP or is there an additive to bring it back up? Cheers sft42