Merry Christmas everyone. I have relocated & my local servo does not sell 98 fuel which is what I have always been advised to use in my 69 Cooper S. Is there any reason not to use 95?

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Life advice
Don't wait for the storm to pass
Learn to dance in the rain
OR
Go drive your MINI

In the absence of 98, 95 should be fine unless you have a crazy high compression ratio.

Thanks for the reply. It is only going to be a one off as I am low on fuel & it is 50 minutes drive to the closest 98 supplier. I will keep a supply here at home for the future now that I am aware.

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Life advice
Don't wait for the storm to pass
Learn to dance in the rain
OR
Go drive your MINI

I figure if it runs on 95 without pinging then there is no reason to run 98, except perhaps a margin of safety if you get some dodgy fuel?

They may advise you to use 98 because it's the safest option, it's less likely to ping but unless your car is tuned for it, it won't make a performance or economy difference IMO.

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Roads need more corners
A Deluxe(CG13DE), 2 Clubbies(998 and 1275) and 2 Morris 1100Ss

If it's a real Cooper S with its 9.75:1 C/R I would only use 95 in an emergency. They NEED 98.
Back in the day we used to add methyl benzene or benzol to 97 octane leaded Super fuel to stop them pinging....!

Exception- IF you have put a big cam in it, it's then less likely to ping.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Fair enough.

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Roads need more corners
A Deluxe(CG13DE), 2 Clubbies(998 and 1275) and 2 Morris 1100Ss

My 1275 is somewhere in the region of 9.8-10:1 and has a decent cam... It tolerates 95 in an emergency if driven carefully, but really needs 98 unless there is no other option as the Doc says.

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*witty signature*

Sapphire Blue Deluxe spread across three parts cars, two sheds and a driveway...

Like the rest of the guys 95 should be ok put if you hear it pinging you need to back off and drive it to the conditions.
Ive been in that situation my self and it was ok.
Rob D.

My engine has 11:1 comp ratio (big cam tho as Doc pointed out) and used for 5 years with 98 RON fuel. On occasions I've had to top up with 95, no detonation cruising around. Even in Indonesia I had no problems (96 RON from memory). I carry some octane booster but never used it.
As an aside, Toluene or Xylene are very cheap, easily available and both have RON's above 120 and are excellent octane boosters. Commonly sold as paint thinners, do not splash it on the paintwork!

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67 Deluxe
Dry suspension
1293cc, 11:1 comp, RE 282 camshaft, 45 Weber, extractors etc
4 synchro close ratio gbox
Cooper S brakes, no booster
Stealth box, as Doc says "goes harder and idles!"
RH tank cos I needed it crossing the Nullarbor etc..

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"Show me the Mini!"

And your point is..?

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67 Deluxe
Dry suspension
1293cc, 11:1 comp, RE 282 camshaft, 45 Weber, extractors etc
4 synchro close ratio gbox
Cooper S brakes, no booster
Stealth box, as Doc says "goes harder and idles!"
RH tank cos I needed it crossing the Nullarbor etc..

https://www.choice.com.au/transport/car ... in-repairs

https://www.sciencedirect.com/topics/ne ... ce/toluene

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"Show me the Mini!"

Hi 69Cool...I'd keep a check on the duration of how long your going to store the 98 Octane at home as the octane rating (especially 98...) will start to lose its RON over a short period of time if you don't use it in your car.

98 octane fuel lasts approximately 3 weeks before the particles that create the "kick" start to diminish.


I've running my S on 95 octane starts much easier if left for some time and has no issues

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