Leaded fuel in an unleaded engine?

[lankybob]

What happens if one was to put a lead additive in a car that runs unleaded fuel?
Anything spectacular?

And in case anyone was wondering, I haven't put any in my car.

[rhinochopig]

pre cat nothing, with cat = knackered cat.

[JAHetfield]

It will run but may damage the catalytic convertor.

[marshalla]

Depends on the additive. The engine would probably run just fine, but the catalytic converter could be damaged.

[TVR1]

Cat will be destroyed, MOT will be failed, wallet will be lighter and you will cry at the cost of a replacement....

[redgriff500]

marshalla said:

Depends on the additive. The engine would probably run just fine, but the catalytic converter could be damaged.

^^^ This.

As they don't add lead the CAT may be fine, but it may not.

[martin84]

[cuprabob]

Why would you want to.

In olden days lead was required in fuel to "lubricate" valve seals /seats.

I'm not aware of any benefit of adding lead to a car designed to run on unleaded other than to feck the lambda probes and cat

[marshalla]

cuprabob said:

In olden days lead was required in fuel to "lubricate" valve seals /seats.

The lead (actually tetra-ethyl lead) was there to prevent knock in higher compression engines. Lubrication was a useful side-effect which allowed for cheaper processes to be used when making cylinder heads, but was definitely not the primary purpose.

[rhinochopig]

marshalla said:

The lead (actually tetra-ethyl lead) was there to prevent knock in higher compression engines. Lubrication was a useful side-effect which allowed for cheaper processes to be used when making cylinder heads, but was definitely not the primary purpose.

Valves seats in particular would suffer if run on unleaded.

[chris1roll]

cuprabob said:

Why would you want to.

During the last fuel protests I had uncatalysed cars. At the time Sainsbury's etc were still selling LRP.
I never had any trouble getting fuel.

You can still buy proper leaded fuel from select outlets, so perhaps this is what the OP had in mind.