Thread: Different Petrol Types

I run the lower grade premium in my Rangie. I would run standard unleaded, but it is not available here (Opal fuel only). If I was using standard grade, I would still use premium for every 3rd or 4th tank (or on a trip) to get the benefits of the detergents, etc.

There are good reasons and bad reasons to use specific "premium" petrol grades.

Higher octane rating is less likely to "ping" so high compression engines (>9:1) should have 95 octane (91 being standard). Modern engines will electronically detune to compensate if run on 91 but there is no performance gain from the petrol.

I don't know the compression cutoff for 98 octane but must be about 10:1 and therefore it won't affect Land Rovers!

The cleaner stuff I don't know about, but if you DO want some, perhaps buying it in a bottle would work out cheaper?

In short - use high octane if your engine needs it, and not otherwise. My County needed it - worked high-compression motor. And I gather from about 1/2 way through Disco 2 production the compression jumped from 8:1 to 9:1 (marked on the head) and higher octane is required.

When I use premium 98 In my Rangie I find I get slightly better fuel eco, my Brother finds the same in his Disco 2 V8.

Although the performance difference is marginal with a low comp engine I run 98 to cope with the higher advance I'm running for LPG, 95 is marginal and pings if I give it a bootfull, 91 is for mowers

Originally Posted by oldzook

91 is for mowers

Not my mower!! Premium only. I figure that I use less than 5 litres per year, I can probably afford to stump for the good gear!

Originally Posted by oldzook

91 is for mowers

Ouch! Cutting comment

In seriousness, you really only need the good stuff if you have higher compression engines. The expensive stuff can give marginly more ecconomy, but it's rarely enough to justify the extra cost. If I had a petrol Rangie I'd put the cheap stuff in, and then once every 4/5 tanks I'd put some good stuff in as it has more detergents and is good at cleaning things.

Our fiesta has a 11:1 compression ratio. On standard it pings noticeably, on premium (96 ron) it pings very occasionally, and it loves 98. My ageing Lotus won't run on anything less than 98. If the fuel is more than a few weeks old it will ping on that too.

Steer clear of the ethanol blended stuff. Ethanol has less energy so you'll end up using more fuel. 3c a litre is not enough to justify the higher consumption.

Originally Posted by Captain_Rightfoot

..........

Steer clear of the ethanol blended stuff. Ethanol has less energy so you'll end up using more fuel. 3c a litre is not enough to justify the higher consumption.

NSW is planning 2% ethanol required in all petrol by next year.........

John

I normally use BP Premium 95 RON. I have trialled BP Ultra 98 RON & thought it was better, but as I don't really need it, I stick with the 95.

I also regularly use Morey's Upper Cylinder Lubricant & that is supposed to be an Injector Cleaner as well. I did use Nulon Injector cleaner previously & that seemed ok, but not now.
At last look, engine seemed to be clean.