Morris Minor Owners Club

What's the best petrol for Morris Minors?
I am using premium unleaded but I think it maybe the cause of my car jumping quite a bit as I have just had it services with new spark plugs and timer adjustments.
Thanks
Mark

Good old 4-star, but your can't buy it now Of what is currently available, standard unleaded is fine. If you have an unleaded head fitted then no need for additives. If no unleaded head, then you may wish to add Catrol Valvemaster. Note that opinion is strongly divided as to the need for a lead substitute.

Thanks
How do I know if I have an unleaded head fitted?
Is unleaded premium unsuitable?
Thanks
Mark

Cyril wrote:Thanks
How do I know if I have an unleaded head fitted?
Is unleaded premium unsuitable?
Thanks
Mark

I don't think there is a visual way of knowing if cylinder head has been converted to unleaded. If the previous owner had the work done I think they would have mentioned it. As previously commented, lot's of Moggies are running quite happily on unleaded with unconverted heads - including my daughters' 948, I started her off on additive but she thought it too expensive.

But what about unleaded premium (which I have been using) compared to regular unleaded? would this make a difference?

if you can get leaded petrol then use it it must be expensive ,i dont thimk many garages stock it now

mis read your post normal unleaded is 95 octaine and the go faster stuff 97 to 100

Cyril wrote:But what about leaded premium (which I have been using) compared to regular unleaded? would this make a difference?

Dear Doctor Who, Where are you getting leaded petrol from?

sorry meant to say unleaded

Cyril wrote:sorry meant to say unleaded

Ah, you mean 'Shell V Power' and the like. This is just a higher octane than standard petrol. Designed for high performance Ferraris ect. Of no use to Moggies I'm afraid. However I did find a very amusing web site called 'Petrol Direct' who state;

'Leaded Petrol

We sell the genuine article at Petrol Direct - real leaded petrol instead of LRP. A little bit of lead never hurt anyone'.

and

'Ultra Low Cost Value Unleaded (50 RON)

Especially popular with Rover Metro and Nissan Micra drivers, our 50 RON ULCVU fuel is made from refinery leftovers. This is a very inexpensive fuel indeed as it is actually classified as industrial waste rather than fuel.'

Surely some kind of send up?

Guys!!! I am getting very very conflicting views here and not just from this forum. Some say super unleaded is better for old cars that are not used to unleaded, yet others are saying the opposite.
At the end of the day do you think this is the cause of my car jumping, kangarooing slightly when accelerated bearing in mind I have just had a full service?

Its ok
Contacted a Morris Minor centre in East Sussex and he confirmed Super unleaded.

My Morris van had an unleaded head fitted to it by the previous owner and I use normal unleaded.My MG Midget has not got an unleaded head and I use normal unleaded petrol in that and been running on that for over twenty years.As long your not going to thrash it it should run fine.

Anything like "Super unleaded", "Premium", "Extra", etc is just a waste of money. Stick to regular unleaded, the car will be fine. If you do a lot of high speed motorway work then I recommend Valvemaster, but, as I noted in my original reply, opinion is strongly divided on the need for it. On what we all agree is that you do not need anything more exciting than standard unleaded petrol.

I have never used 'super unleaded' in my minors, ordinary unleaded is fine for a minor. Super unleaded is really only for modern high performance vehicles.

simmitc wrote:Anything like "Super unleaded", "Premium", "Extra", etc is just a waste of money. Stick to regular unleaded, the car will be fine. If you do a lot of high speed motorway work then I recommend Valvemaster, but, as I noted in my original reply, opinion is strongly divided on the need for it. On what we all agree is that you do not need anything more exciting than standard unleaded petrol.

Spot on! Which leads me to suspect your Kangaroo problem is a mechanical/electrical issue. Have had similar problems with MG Midget and MGB - turned out to be nasty cheap distributor rotor in one case (tracking short through thin and not well insulated plastic material), other was due to nasty cheap condenser (fixed by fitting an old one that had been lying around for about 30 years!). I've even had a intermitent power short from a cheap and nasty distributor cap on a MkII Triumph Spitfire - shorting through the metal spring clip retainer. What does the garage that conducted your recent 'Full Service' have to say about your problem?

The only difference super unleaded will make is to your wallet

Don't know where you're based but Platts of Marlow used to sell four-star.

Platts of Marlow
Oxford Rd
Marlow
Bucks, SL7 2NJ

Phone: 01628 890101
Fax: 01628 894110
Email: marlow@platts.co.uk

Opening Hours:
Mon-Fri: 8.00am-6.00pm
Sat: 8.00am-1pm
Sun: Closed
Bank Holidays: Closed

I used to treat my Moggy to a couple of gallons the real stuff now and again - and she loved it! However, I now use super unleaded which has an octane level similar to good old four-star and is more suitable for an engine with higher compression, like mine. Apparently, super unleaded also has less of the corrosive nasties of regular unleaded.

There seems to be some confusion regarding octane rating and the lead in petrol, which are 2 different things. Super unleaded is higher octane than standard unleaded, which means that it is less likely to cause 'pinking' which means that you can advance the ignition timing slightly further and get a little more power from the engine. That's all, and bear in mind that back in the day, it's more likely that Minors would have run on a lower octane petrol (like pool petrol, or 2 or 3 star) than 4, or certainly 5 star.

Lead (actually tetra-ethyl lead), which used to be added to all petrol, was to stop valve seat recession by providing lubricity to the valves, and also to the stems. It also helped prevent pinking. The jury's out as to whether you actually need it in an A-Series engine, whilst some people use a lead substitute additive, plenty don't, and seldom have problems with valve seat recession and subsequent burnt out exhaust valves.

So, anyone who tells you that you need super unleaded is wrong (though you may or may not get an extra bhp out of it!). Normal unleaded will not make your car run badly, that will be due to something else. If you hear the engine pinking under load, retard the timing slightly until it goes away. Regarding additives, use one if you like; most people seem to think it's wise if you're doing a lot of high speed running (such as motorway driving), but if you do use one, make sure that it's one that's recommended by the FBHVC, as some of them are supposedly rubbish.