Been using 99 RON in both our old 5’s since retiral a few years back.
I “feel” the 2002 car “seems” to run a tad sweeter.
I don’t think the 93 Mk1 gives a toss.
Our rational is we rarely use either now no longer work daily vehicles, might as well give them the best anyhow since the overall % of monthly budget no longer has any impact or is even measurable to any degree. Maybe 2 tanks to a month for the Mk1 at most, and two months to a tank for the Sport. If that.
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Well, a MINI in the family gives abut 47-48mpg on my Mrs commute to work on ordinary Shell or ordinary Esso
(See how many miles done since last fill, divide by the number of litres you’ve just put in, then multiple by 4.54609, gives a 100% accurate mpg since last fill)
On V power, or ESSO’s finest, it gives about 53-4mpg (I kid you not), sometimes about 56.
That’s a consistent pattern too. And not counting the first 2 or so fills when changing to a 95 or 99RON fuel, as it would be effected by some remaining stuff still in the tank otherwise.
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If the ignition timing advance hasn’t been done then your NA is happy to run on as low as 89 RON (I hope I’m remembering that right). So I’m not surprised there is no difference between 95 and 99 RON.
I’ll be running super in my NA just to be sure when E10 comes out. I only do about 1500 miles a year in it so I doubt too many polar bears will be getting their feet wet as a result.
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Good point.
Still on 10 degree ( OEM?) Never did 14 degree with this 2nd engine.
I did with the first, but being an 1840cc Auto, I felt I was gaining a bit at the top end, but losing a bit of lower rev punch…which I did not think suited the torque converter quite so well.
Or, it may well have been a load of tosh in my imagination…it’s ten years plus now.
TBH, this 2nd engine is an real peach…came out a last of line low miles 1998 I think and far better than the original oddly. I’m inclined to leave it!
The higher E rating will perish rubber fittings around the engine if they weren’t chemically designed to cope with the corrosion which the ethanol introduces.
From the gov site linked above, I believe the NB is fine, but the NA may suffer.
I don’t know how much difference it makes to the combustion itself, though you’ll hear a million varied opinions on the subject if you stick around! 
As our 2006 NC uses same engine as 1.8 Ford Mondeo I checked out Ford E10 compatibility which stated all ok except ‘1.8 SCI 2003 to 2007’. Checked this out with local Mazda service department where a young lady told me that as the ‘L’ engine was a Mazda engine used and adapted by Ford, not the other way around there should be no problems. However as we do low mileage I will probably use ‘super’ from now on.
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I have an MX5 Trilogy, first registered on 30/01/2003. It has an 1800 cc engine No BP528996. I believe it is identified as ‘NB’. From what I’ve read elsewhere, NC MX5s are the oldest ones that are E10 compatible. I’ve also read that it can be ‘re-mapped’, which I presume means re-tuned, to be compatible.
Can anyone throw any light on this? Is there somewhere in Kent that can do the re-mapping?
1/ Mazda has said any car manufactured after 2002 is compatible with E10 fuel.
2/ As far as I know the issue hasn’t got anything to do with engine mapping. The problem is the material your fuel tank, fuel lines and some other materials used in the build of older cars that will corrode when using E10 fuel over time. You may have to add an additive to the fuel if using E10 otherwise you stay on the higher octane existing E5 fuel which will still be available at the pumps of Shell, Texaco, Esso and BP garages which a lot of supermarket pumps don’t have. This will start in September of this year. I have a 2000 reg NB and have already started running it on the higher octane with no problem apart from the the higher price per Litre. Although I have a friend in the U.S.A. Who has been running his MK1 Miata on E10 for some time and has had no problems whatsoever.
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Agree with above as I understand it.
Also I understand that the higher octane fuels, e.g Shell v-power will remain at E5. This is the option I’ll take on my 1990 NA
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Thanks for your responses so far. Sounds like the higher octane fuel is the way to go.
There’s an article about this on page 10 of the latest Softtop Hardtop magazine.
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It’s an informative read isn’t it! I agree with the previous replies, I stick with shell V power, it may cost a pretty penny, I’m happy to pay it with my 5 being my second car.
It is important to read the article referred to. As I understand it the critical date is not the date of manufacture but the date of design and first production. So my 2005 Mark 2.5 Arctic is not necessarily exempt from problems. Those of us with classic motorbikes have already had problems with E5 with things like rubber in fuel taps, pipes and carburettors. Have had to go to Viton equivalents to overcome these problems. Would have expected the American aftermarket companies (Flying Miata etc) to have come up with a kit to replace any problem parts if the problem had been significant in the States. I have used Shell VPower for a long time in my MX5, the additional cost is insignificant in the long run for the fun car.
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Yes I think this is the way to go for the older ones, You can also use the half and half method. Half of the new stuff and half Super. Eventually it will have to be a bottle of additive instead.
Some Esso super brand pumps (I have read) are ethanol free.
Quote
What’s in our Synergy Supreme+ 99 premium petrol
Our Synergy Supreme+ 99 petrol has more cleaning power than our regular petrol – and includes molecules whose job it is to reduce the friction in your engine helping the moving parts work more efficiently.*
Although our pumps have E5 labels on them, our Synergy Supreme+ 99 is actually ethanol free (except, due to technical supply reasons, in Devon, Cornwall, North Wales, North England and Scotland). Legislation requires us to place these E5 labels on pumps that dispense unleaded petrol with ‘up to 5% ethanol’, including those that contain no ethanol, which is why we display them on our Synergy Supreme+ 99 pumps.
There’s currently no requirement for renewable fuel, like ethanol, to be present in super unleaded petrol although this could change in the future, in which case we would comply with any new legislation.
Unquote
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I suppose it all depends on how long they keep the higher octane fuel at the pump after E10 comes on line and how long before they try to faze out all old vehicles from the road with environmental legislation 
I’m not sure there is a definitive answer that we could point to and say this is it, I think everyone needs to make their own mind up based on the information in the public domain, the government site should be a reasonable starting point.
I have combined some of the E10 threads together so if the chronology becomes a bit strange that’s likely why.
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So does anyone know which components are not E10 “ready” on MX5 mk2.5 is it just fuel lines are we looking at much bigger issues?
Also been seeing lots of posts on the lines of it will be ok as long as the car doesn’t sit too long with e10 in the tank/fuel system, in which case probably ok if its your daily driver but not in a weekend car…but surely the components with the weaknesses will still be in contact with the fuel.
I’m very confused with all of this tbh, so I guess the only thing to do is to buy premium fuel which will gradually increase in price as less companies do it…:-/
Here is a pretty good article I found interesting. Read through the posted comments as well, but you still won’t have an answer! Some colleagues in France have been using E10 in their MX5’s (all marks) and report no problems.
Personally, as my Eunos is a “fun car” I will run it on Super as the increased fuel costs will be wiped out by one less take-away a month ( if it comes to that sorry state of affairs).
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