Optimax weirdness

[RobM]

With my previous chim 400, I used to get more mpg from a full tank of super, than that of a full tank of normal unleaded. I presumed this was cause super has the higher octane rating. BUT with my 500, I find that I get more mpg with super, than with optimax, but optimax is a higher octane rating than super ?? Anyone else find this ? Any chemistry chaps out there know how to test the octane rating? Some pregnancy test thing that you could dip in the stream or something ?

[McNab]

Rob, they certainly claim that Optimax has the highest RON of any UK fuel - you will have read this on their website, and they also suggest better fuel consumption. The site has an email button and it would be interesting to ask them why you are getting less mpg.

By how much has the mpg decreased, and have you noticed any performance improvement? I was looking forward to using Optimax when it comes to Scotland, but from what you say I may be in for a disappointment!

Would it be worth trying another filling station, just in case there has been contamination at yours?

[steveab]

I've being using optimax for about 3 months now. But the other day I had to fill up with BP Super (I used to use this b4 Optimax). Now I'm not sure.

I've been doing alot of driving recently and it seemed like I got about 270 miles on BP Super (driving between MK and Exter - M-ways) and 260 miles on Optimax (MK to Norwich). Obviously the roads are different but my avg speed was about the same (since it was piddling down when I went to Exter).

I think I'm going to carry out some more tests (because I'm sad!!).

I still rate optimax, since there seems to be less carbon? in the emissions (most exhaust pipes seem cleaner in the inside?!), would suguest that the engine is running most efficiently, ie longer / more complete combustion.

Other than BP super and Optimax, I've not put anything else in mine. I'm curious to know what other 'Super' people are using.

Steve

[hertsbiker]

I notice a huge difference in my tiddler car - it holds 5th & 6th much better WITH, but it does less MPG as well.

I can tell what petrol is in the tank within 100yds of filling, it makes that much diff.

Also it reduces the 0-60 from 13 seconds to 12. (which for 600cc ain't bad).

But IS IT SAFE ??

By the way, I have upped the boost on my trolley to 1.2 bar, from 1.0, which is apparently as much as my turbo will produce reliably.

Carl

[RobM]

quote:

By how much has the mpg decreased, and have you noticed any performance improvement? I was looking forward to using Optimax when it comes to Scotland, but from what you say I may be in for a disappointment!

Would it be worth trying another filling station, just in case there has been contamination at yours?

I tried 4 tanks super, 4 tanks optimax, same journey.. 180 miles per full tank of super, 150 with optimax. Noticed no performance increase/decrease with either.
Contamination !, dunno, could be its standard 95 ron, but I've had no pinking. Optimax is 74p a litre here though, super is just over 80p. I'll try the website. I'll let you know what they say.

[apache]

my car sulks by pinking furiously if I put anything other than optimax now, as for mpg, it seems the same