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lead additive
Posted: Thu Dec 11, 2025 9:41 am
by moggiethouable
For those that use lead additive, how much per full tank of fuel would you use ?
Thanks.
Re: lead additive
Posted: Thu Dec 11, 2025 10:22 am
by simmitc
It depends on the product, they all have dosing instructions. Before fitting an unleaded head, I used to use Castrol Valvemaster where the bottle had a built-in measuring chamber, and one just squeezed until the liquid reached the mark for the number of litres of petrol that you were about to buy - put the additive in the tank first, then filling with petrol mixes it as the fuel swirls round.
I have seen some products that say add the whole contents per tank of petrol, without knowing the size of the tank. so the actual dosing would vary significantly

Re: lead additive
Posted: Thu Dec 11, 2025 11:24 am
by moggiethouable
Fair enough, thank you.
Perhaps an unleaded head may be the way to go one day,
Re: lead additive
Posted: Thu Dec 11, 2025 11:30 am
by svenedin
I use Tetraboost which is actual tetraethyl lead not a substitute.
My engine has an unleaded head so many people, or even most people would say additives are not necessary.
These engines were designed during the lead era and imho they run better with leaded petrol.
The dilution of Tetraboost I use is 110:1
I carry a measuring cylinder, gloves and a funnel in the boot of the car. It is necessary to know how many litres of fuel have been added to the tank and then do a calculation (which I do on my phone). E.g filled up with 20 litres =20,000 ml divided by 110 =181ml of additive to be used.
Tetraethyl lead is VERY poisonous so if you do use it you must be extremely careful especially with the concentrate. In common with many organometallic compounds, it is absorbed through spillage on the skin so gloves must be used.
In terms of damage to others from exhaust fumes this was a major issue when all fuel contained lead but with minuscule numbers using it unlikely to cause harm.
Stephen
Re: lead additive
Posted: Thu Dec 11, 2025 1:39 pm
by moggiethouable
No its not Tet, but any chemical is to be handled with kid gloves of course.
Thanks.