
Originally Posted by
Old Steve
There's been a fair bit of misinformation in these posts. I worked for Caltex for over 20 years, worked as their Technical Manager in NZ for a year and a bit, represented the company on the team which liaised with Govt and introduced unleaded petrol in NZ, and worked for over 8 years in cCltex's International Technical Center in Sydney (mainly on lubricants, but did some work on fuels). I am a bit biased about Caltex, I like their petrol additive technology. Worked on getting Caltex their BMW approval for their additised petrol, and that's a story and a half. Haven't worked in the industry for nearly 10 years now though.
There's 2 different octanes. Octane is the measure of a fuels resistance to knocking, preigniting. RON and MON, one is Research Octane Number and refers to the fuels resistance to knock under high speed, other is Motor Octane Number and refers to the fuels resistance to knock under low speed high load conditions (such as pulling away from a corner in a higher gear. The NZ fuel specs have a minimum limit for both RON and MOn, there;s usually a 10 number difference, MON is lower. The less difference, the better the fuel is. So 91 has lower limits of 81/91 for MON/RON, 95 has limits of 85/95 MON/RON. There are also limits on the aromatic content, volatiliy, olefin levels, and a whole lot of other factors. American "octane" is RON + MON / 2, so 'standard 91' here is 86 there, 95 here is 90 or 91 there. It's that simple
Auckland is the only area which gets pure Marsden Point petrol through the piupeline. BP, Caltex, Mobil and Shell (or Greenstone actually) are all partners on WOSL, Wiri pipeline terminal. Gull tankers into Auckland from Mt Maunganui I think. A lot of the rest of the petrol used in NZ is imported, usually from Thailand or Singapore. Marsden Pt petrol is VERY good, when Caltex did it's BMW tests in California we had to ship 200 Litre drums of unadditised petrol to San Fransisco for the tests. They landed the day of the earthquake there and went missing for 2 weeks. Was found, additised and the test was run, and BMW rang the additive company asking what new technology they had because the results were the best they'd ever seen - that was largely down to the quality of the Marsden Pt petrol and the additive technology combined.
But the base fuel in any area is completely the same, tanker comes in and fills all the comapny's tanks. It's the additive which makes the difference. Petrol leaves deposits on the back of valves in fuel injected engines, and gums through carburettors. These valve deposits absorb fuel when a rich spray is produced on start up),making starting difficult, then the fuel evaporates out of the deposit when the engine has warmed making the engine run rough. The additive should clean these valve deposits, and clean out carburettor gum. On the BMW test, they weighed the valves before and after running 5,000 miles I think, could have been more. The Caltex valves had no weight gain, absolutely no increase in weight - BMW had never seen anything like it.
Using 95 if your engine only needs 91. I don't believe it helps. If the engine has an electronic management system and knock sensor then it will advance on the higher octane fuel and you may see a small increase of fuel economy but I don't think its worth it. Using Gull, I wouldn't as some polymers used in fuel systems might not be compatible with ethanol. I just use Caltex Techron 91 in GLORIA (though there are some on this forum who think Hyosungs would run on pig urine - they won't by the way).
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