MGB Register Forum

Newly bought 1976 MGB GT V8 - just found a bottle of Wurth lead substitute! Now I never gave it any thought but is a 1976 V8 likely to be designed to run on leaded petrol? If so, will using lead substitute do or will I have to get the heads updated?

Because the Rover V8 engine is all aluminium, including the cylinder heads, it already has steel valve seats inserted. If it didn't the valves would quickly batter their way through the aluminium. So, no you don't need a lead substitute, and what's more you don't need a high octane petrol. After all, what you have is a low tune basic Land Rover engine, designed to be used in the far flung corners of the world where you take whatever fuel is available. I ran my V8 for years on standard supermarket petrol without an issue. I am putting the super grade in now to get away from 10% ethanol in ordinary petrol. The cost hurts but hopefully it might preserve my fuel system.

unlike the 1.8 B series there was never an issue with unleaded fuel on the V8. Being a rebadged Buick engine it was designed from the start to run on unleaded fuel many years before unleaded was available in the UK

Thanks guys - I'll throw the Wurth lead substitute in the bin. However will use Shell E5 RON 99 fuel just to keep the ethanol down. What a waste as the engine is very low compression so does not need the high octane rating I'm paying for. Only solution is to fit a tuned higher compression head!

And don't forget you'll need two....

I run the GT on Super and even though it has hardened valve seats, I still use Millers fuel additive in it.

I have to run my 1975 Land Rover on super unleaded even though the engine is 8:1 compression and it's 17p a litre dearer than E10 rubbish. It has a 1985 2.5 litre engine which was fitted with an unleaded head at the factory from new. No need for expensive unnecessary additives. My MGB has an unleaded head as well but I think it's cracked as overheating occurs.
The Land Rover runs very well on super unleaded. I have to use super unleaded in my chainsaw, strimmer and hedge trimmer too.