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What is the difference between super unleaded petrol brands?

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What is the difference between super unleaded petrol brands?

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The RON number refers to Octane, which is an indicator of the petrol’s resistance to “knocking”. This was important in the days when car engines were very different from today’s. Up until the universal adoption of computerised engine management systems (about 15 years ago) you could get engines with compression ratios that varied considerably more than they do now. The high compression engines needed higher octane fuels to run properly. That’s why there were up to four different types of petrol available: 2*, 3*, 4* and 5*. When unleaded became universal the higher octane petrols were gradually phased out because the modern engines mostly did not gain any performance advantage from them. The lead-substitute additive gives all the anti-knock performance needed. Modern engines do not have the wide variations that older ones had and so they can run on similar petrol octane ratings. Mostly 2* these days, that’s why they don’t bother marking star rating on the pumps. The difference in car e

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