Finally got the vRS :))))

cheers - i sort of knew that but didn't actually if you know what I mean. I'll get my coat.

Run it on 98 it will make a difference, The timing will retard or advance to what fuel you put in, the better quality the fuel the faster the car goes, its been proved many times on Dyno's in USA that the higher octance fuel will make you car run better.

Most after market remaps advise you use higher octane fuel as well.

Ronny

Yes, a negligible one tho and one that's generally a personal thing as to whether the perceived fractional difference is actually worth the extra outlay involved in using more expensive petrol. The theory is that the higher RON juice will give you more MPG, but will it be enough to make up for the extra pennies...

No.

Any gain from 98-RON fuel is teeny tiny - certainly not worth the extra cost.

Unless your car REQUIRES it (ie, a few Jap cars, and some things in a very high state of tune) then there's no point using it.

Feel free to try it yourself, just so you know !

I've heard it said that cars with a knock sensor and computer controlled ignition timing (like mine) can take advantage of higher octane fuel by adjusting the timing to raise compression / power.

Seems to be about break even, i.e. the higher cost of the fuel is offset by the extra mpg, unless I'm imagining it.

The v8 runs cooler on higher octane though, which is a dead good reason for it there, not seen any difference in performance / mpg.

Yes, they can.

However, the "advantage" gained is so small that you'll hardly even notice.

My current car and my previous car were both knock-equipped, and both had proper electronic ignition (ie, no dizzy cap). Higher octane fuel did a smidgeon more than bugger all in both. Same applies to all of my mate's who have tried it, apart from the RX7 owner who *has* to use it, cos it drives like a dog on normal fuel :)

I only got about 5 - 10 miles extra per tank, out of the higher octane stuff.

Agreed - some cars do like it. Certainly doesn't do any harm using it - but people seem to notice differences that aren't actually there ! I guess it's the psychological effect - they pay more for the juice, so they expect it to do more ?

I think this must depend on car engine / type.

Sommat like 380 instead of 340 here, as I recall. The added miles are similar to the added cost of a tankful, but the car does have a little more power as well. Like, just worthwhile, it would seem. Other people with the same car say a similar thing, for what that's worth. (Not an enormous lot, I know).

Yeah, well I resent paying more so it has to give me a reason.

Seems to *just about* be worthwhile, to the extent that I don't greatly care which I put in the Scorpio. But I do like to use the highest octane I can find for the v8, as it is always trying to overheat otherwise. Don't know what mpg that does, but not a lot, it won't be getting an improve mpg at a guess because it's fixed timing, compression and carb. That's to say, if lower octane was not the same, it would be pinking on the cheap stuff (and presumably it isn't.)

In article , snipped-for-privacy@Somewhere.Somewhere spouted forth into uk.rec.cars.modifications...

The Saab would run noticably cooler on Super and Optimax, because even though it could right down to 92 RON (yes RON) it said in the fuel flap, use 98RON fuel (back in 1984). I guess Swedish 4 star (it was a pre CAT car)and Super unleaded (it came with an unleaded friendly green fuel cap) was a little bit more pokey that tha usual watered down UK stuff.

When using Super, boost climb was a little sharper, but it still went like a rocket when it went anyway.

Temp never varies on the TI - guage sits rock steady at 50%, no matter WHAT the conditions :)

Would run at about 40% normal on a warm do, to about 60% crawling traffic on a warm day or after an extended fast (80+) run of more than an hour followed by normal warm down.

Fan kicked in at about 70-75% of the normal section of the guage (well before it would get to the hot spot).

In winter on a motorway run, the gauge would get barely into the green normal section unless I hit crawling rush hour traffic.

It can be interesting to test the gauge readings against actual temperatures, a lot of gauges (certainly most of the newer ones) don't show variation unless they're significantly out of the normal range.

The old Triumph one I have here shows the actual temperature and goes up and down around "normal" sometimes approaching the "overheating" red bit, but not usually below the "nice and cool" 35 - 40% sort of mark.

Since a car will run warmer and colder, else the booster fans wouldn't turn on and off at the upper / lower temperatures, it's interesting to see the gauge reading exactly the same when the fan turns on (temp is getting too high) and when it turns off (temp has reduced to a tad below normal.)

Course, it's one less thing to worry about, unless the car actually overheats (and then you've missed the warning stages.)

Ask the dealer, mine told me i didn't need to :) But i did a bit anyway, i just drove normally, but without getting to the redline. And, if you've never them before, like me, HOW AWESOME are gadgets :D ?

Mine a Peugeot, so i'm EXACTLY here with you - nothing has fallen off yet, its done over 1000 miles now, nothing has gone wrong, and i've been to the top of the numbers on speedo (130mph) on a dark, windy motorway at 1am the other day :) I was the only one around for miles, couldn't help myself, slight downhill, and i was away :D summet like 16mpg, foot hard down, still pulling at somewhere round 130 indicated, it had more to give, i just bottled out as it was getting too windy.

Run it on whatever you plan to permanently run it on.

:)

Guage works just fine - my thermostat started sticking open occasionally, a year or so back - temp dropped from 50% down to about 10% after a slow down from high speed - got the 'stat replaced, and all was well again.

Fans both work fine, when A. The aircon is turned on, and/or B. I get stuck in traffic for *lots* of minutes :)