JetSet Posted November 26, 2015 Share Posted November 26, 2015 Yes, the last sentence says it all. Petrol sold in the UK must conform to BS EN 288 British Standards. This allows up to 5% ethanol in petrol. Tesco fully complies with these standards with the ethanol content of our fuels varying from 0 - 4.8% depending on the location and supplier. Pete Quote Link to comment Share on other sites More sharing options...
Rock_Steady Posted November 27, 2015 Share Posted November 27, 2015 It makes absolutely no sodding difference whether you use 97, 99 or 105 unless you've specifically mapped for it. As long as the fuel is made to the correct BS, and they all are, then that's all that matters. The 350/370 wasn't made in the 1960s, so it'll be fine Makes a difference if you're running a tubby though. Quote Link to comment Share on other sites More sharing options...
Ekona Posted November 27, 2015 Share Posted November 27, 2015 It really doesn't. Unless the ECU is mapped for it, then you can put in whatever you want and it won't make the blindest bit of difference. Of course, you can run more boost or advance the timing if you're running 105 for example, but again that just reinforces the point that it's all about the mapping. Standard, FI or engine swap, you won't see the difference unless mapped. If you have to run 99 because you get substantial knock on 97, then I'd be having a strong word with the tuner personally, For example, my MR2 runs as happily on 97 as it does on 99, and I notice more difference in the power when the temp drops than I do on any fuel I put in. Quote Link to comment Share on other sites More sharing options...
Wayne370Z Posted November 27, 2015 Share Posted November 27, 2015 It makes absolutely no sodding difference whether you use 97, 99 or 105 unless you've specifically mapped for it. As long as the fuel is made to the correct BS, and they all are, then that's all that matters. The 350/370 wasn't made in the 1960s, so it'll be fine Makes a difference if you're running a tubby though. Definitely. Any passenger over 14 stone is going to make a marked difference on the power to weight ..... 3 Quote Link to comment Share on other sites More sharing options...
Rock_Steady Posted November 27, 2015 Share Posted November 27, 2015 (edited) It really doesn't. Unless the ECU is mapped for it, then you can put in whatever you want and it won't make the blindest bit of difference. Of course, you can run more boost or advance the timing if you're running 105 for example, but again that just reinforces the point that it's all about the mapping. Standard, FI or engine swap, you won't see the difference unless mapped. If you have to run 99 because you get substantial knock on 97, then I'd be having a strong word with the tuner personally, For example, my MR2 runs as happily on 97 as it does on 99, and I notice more difference in the power when the temp drops than I do on any fuel I put in. i see your point but but there is a difference iMO in how a car performs, albeit marginal but enough to make you notice the difference, or at least in my experience. Edited November 27, 2015 by Rock_Steady Quote Link to comment Share on other sites More sharing options...
Ekona Posted November 27, 2015 Share Posted November 27, 2015 There shouldn't be any difference at all, if it's not mapped for it. Any difference will be down to weather conditions rather than swapping between 97 and 99, or maybe even just wishful thinking! Quote Link to comment Share on other sites More sharing options...
nissanman312 Posted November 27, 2015 Share Posted November 27, 2015 There shouldn't be any difference at all, if it's not mapped for it. Any difference will be down to weather conditions rather than swapping between 97 and 99, or maybe even just wishful thinking! So I have a 99 97 and 95 map if I get anything less than 98 99 then I run my 97 map to be on safe side Ian told me its just a couple of degrees timing retarded You can barley feel the difference to be fair Quote Link to comment Share on other sites More sharing options...
docwra Posted November 27, 2015 Share Posted November 27, 2015 There shouldn't be any difference at all, if it's not mapped for it. Any difference will be down to weather conditions rather than swapping between 97 and 99, or maybe even just wishful thinking! Unless you have a 1990's Saab with Trionic engine management, thats the only car I know of that will detect the octane rating of the fuel you are using and adjust timing (and possibly boost and fuelling) to suit automatically. 1 Quote Link to comment Share on other sites More sharing options...
Ekona Posted November 27, 2015 Share Posted November 27, 2015 I was banking on no-one here having one of those 1 Quote Link to comment Share on other sites More sharing options...
Juggalo Posted November 27, 2015 Share Posted November 27, 2015 There's always one smart arse lol Quote Link to comment Share on other sites More sharing options...
Mikey81 Posted November 28, 2015 Share Posted November 28, 2015 I've nearly always use Shell as there are 4 with 2 miles of my house, so whichever direction I go I can fill up easily. Yeah it costs a bit more but it's convenient and the advert says the engine will be better treated due to the additives In my old E39 M5, it made 12 more hp on the same rollers with tesco momentum, not scientific as different days etc but that is a big variance for the same car with no changes apart from fuel between the runs, about a month apart on a standard car. Quote Link to comment Share on other sites More sharing options...
AMT Posted November 29, 2015 Share Posted November 29, 2015 Just stick whatever fuel you want in it as long as its a super unleaded... Wont make any normal noticable difference. The arguments for any version of a super unleaded dont make much point if your a normal person driving a normal car in normal day to day driving... However.... Ive got the fear of using Asda...and never have and I couldnt tell you a reason. Also BPs super rating seems to be lower than reccomended for the Z last time I looked (while ago mind you). Again though you read the HR has a knock sensor or something and should be ok (still wouldnt use normal)... The arguments could go on and on. Everybody just use a well known super unleaded...all will be fine. There ive sorted one of the worlds many problems haha 1 Quote Link to comment Share on other sites More sharing options...
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