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MG MGB Technical - Fuel

Hope I’m not going over something that’s been asked before but here goes,
By mistake I-put £20 worth of e10 fuel in the roadster a couple of weeks ago and am coming to a time of year that the car won’t be used much. I am not happy leaving the car with e10 in the system over the winter so I went to an Esso garage to put fuel in as I had been told Esso do not use Ethanol in any of their fuels but was surprised to see it labelled as E10 or E5 on the petrol pumps. Have I been incorrectly advised regarding Esso fuel.
Trevor Harvey

By law they must have E5 or E10 labels, and they indicate 'up to' 5% or 10%, which includes zero %. This https://www.esso.co.uk/en-gb/fuels/petrol states that everywhere except Devon, Cornwall, North Wales, North England and Scotland have Synergy Supreme 99 at 0%. At the moment.
paulh4

Attached pdf (as at 13/9/21, I've not updated since).

You are best to drive the car to fully use up the £20 of E10 if the car is going to sit around for weeks or months.
Nigel Atkins

Thanks Paul and Nigel, that’s what I wanted to know.
Trevor Harvey

Trevor. I have used fuel having a 10% ethanol content for something over 20 years now. When I am storing a vehicle having such fuel in it, I add fuel stabilizer (Stabil is the brand, I think), store the vehicle for several months, then start it up with no problems. I have used this system and found the petrol (gasoline) good a year later. Do not think it would be a problem with storing a vehicle over the winter.

Les
Les Bengtson

I use mine all year round but only when road conditions are suitable in winter and by spring the fuel can be six months old, no additives. Never any problems but that's always been E5. I'd always used 95 octane in the V8 as it's low compression but now that's gone up to E10 I'm running both cars on 97 to 99 which is E5.

The unexpected thing is that the V8 is now running better than it ever has - smoother, better pickup, and better mileage without having made any changes to ignition or carburation - except having to turn the idle screws down as it was idling at 1200rpm instead of 1000. I'd set it to 1000 to keep it at 850 with the cooling fans on to keep the oil pressure up a bit, but now it's barely dropping when they are on. I'm aware that some engines are warning of impending problems when they run smoother ...
paulh4

Paul,
try a tankful (and not just a top-up) of the Esso (zero) and see if that makes any further difference at all.

I used the high octane Tesco and V-Power pre and post E5 for their additional cleaning additives rather than the octane and found they generally 'felt' better than the 95 octane fuels pre and post E5 the car had been set up on and for.

Last year I tried running on E10 95 and it was no problem but definitely leaner so when I tried Esso (zero) the car 'felt' smoother and seemed to be running richer of course but no more power.

When I had the carbs apart after 35k-miles use from brand new I could see the benefits of using the petrol with extra cleaners or standard 95 with half a bottle of cleaner per six months (tank only holds nominal 26 litres) other than one tiny spec of something that looked like thin card at the bottom of one fuel bowl the carbs were as clean as a whistle fuel side.

When I had my (1800) '74 BGT decades back I generally ran it on the Optimax or whatever it was called then and if I went back to a standard petrol the car might pink under certain circumstances. Had a book from Shell of the stations selling it as it wasn't so readily available especially when touring Scotland and the Shell station closed at 8/9pm.

Nigel Atkins

Higher octanes in a high compression engine should allow you to run with more advance without pinking. I've always run the roadster on high octane except in Scotland when I could only get low, and had to retard the timing on the road (benefits of a 25D4 distributor), after which it ran poorly and hotter.

Never used cleaners, never had a problem with dirt. Esso being the same octane as Tesco I wouldn't expect to see any change in running but may try it. I didn't notice any changes going from ethanol-free to E5. Not noticed any change in the roadster yet going from Shell V-Power to Tesco Momentum 99 - couldn't see the point of carrying on with that once I started using Tesco in the V8.

The only additive I've used was Valvemaster as a bit of insurance against valve seat recession, I tried the octane boosting version but found it didn't allow me to run any more advance, this roadster has always been more sensitive to pinking than other cars, particularly going from leaded to unleaded. Unleaded head now so no more Valvemaster but it's not changed the pinking situation of course.
paulh4

The BGT was on the old CB points IIRC but as you can imagine I didn't bother getting my hands dirty by fiddling around with the dissy as the pinking was only with 95 under certain circumstances so I avoided those circumstances.

1275 midget is 8.8:1 as standard IIRC, the difference on the Midget didn't used to be that noticeable, I expect the electronics at top and bottom of dissy saved me messing about with it as its position didn't move over serval rolling road sessions. I never had to do any dirty hands stuff when I ran on 99 octane but had to use 95 when on holiday driving over the better Welsh mountain roads for a good number of years.

It was going from E10 95 (with Millers VSPe additive) to Esso (zero) 99 that seemed to need carb mixture adjustment. Of course different engines at different states of wear and tune and in different cars will give different results and needs.

Tesco is UP TO 5% ethanol (possibly around 3% I've read somewhere at sometime) whereas Esso (E5 labelled) is zero ethanal and the additive packages will vary. Whether these differences make any odds to any particular car is a another matter.

The Valvemaster (certainly under MGOC) would have also been a part cleaner and of course petrols have cleaners and the higher octane petrols addition level of cleaners.
Nigel Atkins

This thread was discussed between 02/11/2022 and 08/11/2022

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