unleaded fuel vs leaded

[harris66]

something ive often wondered, and a recent thread about 2 star got me thinking again, has anybody actually had experiences of damage caused by unleaded fuel in a car that should run on leaded? most guys I know use unleaded in there oldies, and to date no one has had a problem, even done it myself, I know what the lead in fuel does and the effect it should have when unleaded goes in to a leaded engine, just never seen it, recently did a head gasket on a viva, been ran on unleaded for yrs and all valves and seats looked fine,

[rustybits]

Depends entirely on the individual car. Some valve seats have been perfectly capable of taking unleaded all along.. some arn't.

You just have to ask around about the specific model of car. Of course, if the head has been rebuilt, it may have had better seats fitted at some point anyway.

[dollywobbler]

Our 998cc Mini has been running on unleaded since we got it last year. About 18k miles done. Checked the valve clearances really and not a sausage. However, it does have a "fuel saver" fitted and I suspect that this is one of those in-line catalyst things that are now banded about as miracle cures for cars that need leaded. Perhaps we've just proved that they work!

I rarely own cars long enough to experience trouble although the miniMetro did of course famously drop a valve. Related to too much unleaded use perhaps?

[BenzBoy]

I've never run my car on leaded. Early on I used to use LRP but it was unnecessary as Merc engines all have hardened valve seats from way back.
I have considered lobbing a score's worth of Leaded in the tank, just for novelty and to see if it makes any difference. And so I can give some kids brain damage.

[Seth]

I've burnt exhaust valves out in the Oxford using unleaded. But then B series (and A series) are susceptible to it anyway so who knows whether they would have gone anyway.

We don't bother putting any additive in the Herald as its reckoned the seats are hard enough. Plenty of miles have shown up no problems.

[Seth]

Sorry for double post but just wanted to add that the lower octane rating is certainly noticeable as the cars won't run without pinking at factory advance setting.

[rustybits]

You don't usually have to use half so much additive as it says on the bottle, unless the engine is notorious for the seats going.

Sticking it in every other tankfull is more than enough. Once the seats have their coating of lead, they stay like that for a while, depending on what kind of use the engine gets.

[briandamaged]

I ran a Mk5 Cortina that had been fitted with one of those Fuel Broquet things, it ate a valve but I don't know if that was down to the unleaded or my rock-ape driving though.

The thing I miss most about 4-star is the smell of the engine after a good thrash. That and the gorgeous white colour the inside of your tailpipe used to go if it was running well.

[Mr K]

i was reading somthing the other day saying about talking to a engineer at reliant, who said that despite having different part numbers, unleaded and leaded relaint valve seats all came from the same place, and where all identical, except price! lol!

i smash unleaded in mine, i havent managed enough miles without a major mechanical failure resulting in engine change (not due to unleaded) to say if it has any effect.

[BenzBoy]

You can sometimes get away with putting a tank of leaded in every so often (I don't recall how often...) to keep the "lead memory" in the valve seats.

[charlie]

The story of why lead was added to petrol is terrible and will infuriate you. It is a story of profit at the expense of the health of the population. Essentially lead was mined, it was cheap and it was very poisonous. But the people that used to mine lead made a lot of money from it, so they made it an additive in petrol. It served no purpose apart from making money. And it caused a lot of cancer and illness, and it probably still does.

Charlie

[dollywobbler]

1 in 4 was the recommendation I think Benzboy. Agree with Seth about timing. The only mod needed for 2CVs too.

[BenzBoy]

Thanks for clarifying, Dollywobbler!

charlie said:

The story of why lead was added to petrol is terrible and will infuriate you. It is a story of profit at the expense of the health of the population. Essentially lead was mined, it was cheap and it was very poisonous. But the people that used to mine lead made a lot of money from it, so they made it an additive in petrol. It served no purpose apart from making money. And it caused a lot of cancer and illness, and it probably still does.

Charlie

Really? That's pretty shocking. So was lead's ability to reduce pinking just a side effect?

[harris66]

charlie said:

The story of why lead was added to petrol is terrible and will infuriate you. It is a story of profit at the expense of the health of the population. Essentially lead was mined, it was cheap and it was very poisonous. But the people that used to mine lead made a lot of money from it, so they made it an additive in petrol. It served no purpose apart from making money. And it caused a lot of cancer and illness, and it probably still does.

Charlie

always thought lead was added as a lubricant? is that not the case then??

[rustybits]

The lead lubricates the valve seats.. which prevents the valve getting so hot, which stops the pinking. 2 strokes cool the piston in a similar manner.

[dollywobbler]

Hmmm, not sure about Charlie's story. There is plenty of truth in the fact that it was known to be dangerous and that people didn't care back then - tobacco industry style but lead was also a quick-fix to reduce pinking, rather than having to develop engines to be better able to run on non-leaded fuels.

[Mr K]

the kitten had various chunks of lead and air rifle pellets in the fuel tank when i got it; i guess that turned unleaded fuel into leaded fuel, simple as that. just add lead.

[harris66]

understand the health problems that lead caused and i too understood that lead was a cheap way to do the job in hand, interesting for some back up on the story that lead was added just to line the pockets of the mining industry?

[popuptoaster]

depends on your driving as well as the engine, high revving motorway work will damage valve seats that will be fine in the same type of engine that only potters around town at lower revs.

Ive never bothered with running additives in any of mine as my cars are usually so slow or noisy at sustained high speeds its actually as quick to stay off the motorways and poodle along the A roads, I've never suffered any damage, anything i drive on the motorway has usually had a modern engine dropped into it.

[Seth]

I am of the understanding that lead was added as an octane booster and they subsequently found it had useful lubricating qualities enabling manufacturers to specify lower grade (cheaper) materials for valve seats etc.