MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - Unleaded or Super

I have only just recently purchased my very own 1978 MGB and was wondering which fuel it supposed to run on. The previous owner said that it should run on standard old super which is being fazed out in Australia. The fuel gauge however states "unleaded only." Could someone enlighten me as to the correct fuel type as I don't want to damge my engine.

Stuart
Stuart

Leaded gas won't kill your engine but it will kill the catalytic converter. Unleaded gas generally leaves less deposits than leaded gas.
Mike MaGee

I recommend going with Shell Optimax or Mobil 8000 Premium unleaded (98 Octane) and just to be sure, add the anti-Valve-Seat-Recession liquid to your tank of fuel (they sell it at the counter of the servo). When you next have the head off the motor, check if hardened valve seats have been installed. If not, get them installed and never worry about using unleaded again.

The 98 octane fuel will give you more power (you'll need to bump up the advance on the dizzy though), the engine will run more smoothly and will stop running on and pinging.

James
James

If it has already got a cat hence the 'unleaded only' sticker then it *should* have the unleaded head and will not need the anti-recession additive. Which isn't to say it still has such a head. If it has a cat and the previous owner was using leaded then he has ruined it anyway, which may show up on any emissions tests if you have to pass them. North American-spec cars built for unleaded, which had the 'unleaded only' sticker, were low-compression and I don't know how much benefit you will get from the higher octane. Certainly my high-compression UK 73 runs like crap on standard unleaded, even with an octane booster and anti-recession additive, as I have to retard the ignition to control the pinking. This shouldn't happen on a low compression engine, and if it is a North American spec car and still has the (working) emissions and anti-runon system it won't run-on either.
Paul Hunt

This thread was discussed on 30/10/2003

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.