Question for Rob-Jax

[parker1158]

Hi Robert

A non caravan related question.

You may or may not recall I have quizzed you before on the fuel in my classic car a 1955 Minx convertible. Up untill recently I have used a lead additive namely 'Castrol lead replacement plus octane booster'

The car ran fine on this but a garage near me started to sell good old leaded four star-not cheap at £1.50 a litre but the car runs so much better with it.

So question what is the difference between unleaded with additive and good old four star? My mates say I only notice a difference because I need to justify the excess cost, while I can accept this may well be the case I wondered what your professional thoughts were.

Also a friend of mine with a early eighties ford keeps having to change his fuel gauge sender and has been told this is because unleaded fuel eats away the carbon track on the gauge sender and that he should use an additive to combat this. Putting on both my ex mechanic and science degree studying hats I found this difficult to accept, any ideas?

I'm sure you have better things to do so I gratefully thank you in advance

 

[rob_jax]

Hi Martyn,

I sincerely hope they are not selling 4 star leaded fuel with Tetra-Ethyl Lead (and the organic Bromide scavenger) - that's illegal.

Tetra-Ethyl Lead is no longer available in bulk quantities, so I assume it's a LRP type fuel - and hopefully has no Lead in it at all.

Modern low Sulfur petrol is designed for catalyst equipped cars with electronic fuel injection, and has suitable additives to support the pumps, high pressure injectors and not poison the catalyst.

Recent moves to reduce certain aromatic compounds like Benzene, and the changes to reduce fuel volatility - to stop people being exposed to fuel vapours when filling the tank, probably mean that a modern fuel won't atomise / vapourise in the carburetor as well as the "old stuff"

But what the garage is actually selling (probably LRP at a premium price) is a guess.

Fuel Gauge Sender:

It was just a poor piece of design, and I can't how a modern fuel would affect the carbon track - but it could do.

Try the additive and see if it lasts longer - but a replacement sender that uses different technology would be better.

Robert

 

[rob_jax]

Hi Martyn,

I sincerely hope they are not selling 4 star leaded fuel with Tetra-Ethyl Lead (and the organic Bromide scavenger) - that's illegal.

Tetra-Ethyl Lead is no longer available in bulk quantities, so I assume it's a LRP type fuel - and hopefully has no Lead in it at all.

Modern low Sulfur petrol is designed for catalyst equipped cars with electronic fuel injection, and has suitable additives to support the pumps, high pressure injectors and not poison the catalyst.

Recent moves to reduce certain aromatic compounds like Benzene, and the changes to reduce fuel volatility - to stop people being exposed to fuel vapours when filling the tank, probably mean that a modern fuel won't atomise / vapourise in the carburetor as well as the "old stuff"

But what the garage is actually selling (probably LRP at a premium price) is a guess.

Fuel Gauge Sender:

It was just a poor piece of design, and I can't how a modern fuel would affect the carbon track - but it could do.

Try the additive and see if it lasts longer - but a replacement sender that uses different technology would be better.

Robert

Hi Mitch,

I need to modify my previous statement, I had a quick look at Petroleum Review - apparently it is possbile to sell leaded petrol - but under very strict guidelines - it must be less than 0.5% of the total sales - which now shouldn't be a problem as only classic cars could possibly use this fuel.

It's expensive because of the very high tax imposed on the fuel.

Old unleaded had a density of 0.72 compared to 0.78 for a modern fuel - this means that the old fuel had quite a high percentage of lighter hydrocarbons - which affects the fuels volatility in the carburetor

Likewise, the old fuels will have around 1% Benzene compared to 0% in modern fuels - and whereas this was once sloshed around in laboratories and used for grease removal - it's ability to damage bone-marrow and start cancers means it's best avoided

Obviously Lead will be present at around 0.15 g/litre, and around 40 times the current Sulfur level too.

None of these components are good news.

But yes, as long as total sales are less than 0.5% - you can buy leaded petrol.

Robert

 

[parker1158]

Hi Robert,

Very interesting. I understand about aromatic carbon chains as we touched on refining fuels a couple of years ago although my studies are more in the environmental sciences obviously car pollution comes into that.

As far as I am aware it is proper four star, it seems a very limited number of garages are allowed to sell it and this particular garage are classic specialists so I guess this helped them obtain accreditation.

I only do less than 500 miles a year in this car so I am prepared to take the risk from the fuel. Out of interest are there the same health dangers from the additives or isn't it 'real' lead and other noxious substances. The reason I ask is if I use additive it invariably gets on my hands and clearly I am breathing in the fumes whereas at the filling station would you believe they are so old fashion that they have an attendant who fills your tank so I don't directly come into contact with the four star.

 

[rob_jax]

Martyn,

The additives should (or could) be lead free, and the modern fuel is formulated so that there are less issues with it.

And don't let any petroleum fuels or additives or lubricant oils, etc., get on your hands - either buy some disposable gloves or use the freebie gloves found at petrol stations.

One of the reasons for reducing Benzene in fuel was becuase of a concern that pump attendants could be (just possibly) seriously exposed after years of service - particularly in hot countries like Spain and Italy.

Robert