: Leaded gas in '72?

08-02-13, 05:50 PM
So my father and I have spiritedly debated this question among ourselves and our Car-savvy friends. We have a 1972 Sedan Deville with a 472 engine. Both of us always assumed it took leaded gas. When my dad drove it in college, he said he always added a can of lead additive to the tank, because he remembered his grandpa buying leaded gas. Now that I drive it we haven't been adding anything to it. Everyone we ask seems to be on the fence if a lead additive is necessary or even available anymore (Something makes me think it's illegal). So my question is should we be adding lead or a synthetic alternative to the gas tank or is it better off with just plain old premium gas?

08-02-13, 06:18 PM
GM went low compression, lead-free engines fleet wide in 1971.

The Ape Man
08-03-13, 11:11 AM
This series of engines uses quality components and doesn't require lead.

08-03-13, 06:35 PM
My wifes aunts car required lead gasoline and it was available here in El Paso..don't know where exactly but that's what she put in it.
She was the original owner and recently scrapped the car. Oh, and it wasn't a Caddy. It was a Pontiac Catalina with a 400, coupe.

08-03-13, 06:54 PM
In the early 70's the amounts of tetraethyl lead in gasoline were gradually reduced. One of the engine wear problems addressed by tetraethyl lead additives was valve seat erosion - the lead "cushioned" the seats/valve faces. To counter the decreasing "lead" amounts valve seats were flame hardened and that took care of the problem through the MTBE years to the now-ethanol years. It is common practice to machine old cylinder heads and hydraulically press-fit hardened valve seats - rings - during overhaul.

If you want to spend the extra bucks for warm and fuzzy "lead additives" go ahead - but if the engine was set up for the decreased lead additive levels it doesn't need extra snake oil. ??? Set up ??? - Service manual and owner's manual guidance.

"Quality" has nothing to do with the problem - technology and engine evolution does. An engine that required leaded fuels (my as-delivered 1965 327/350 Chevy for one) is just as high "quality" as any engine today.

Leaded fuel - When did catalytic converters become mandatory ?? Tetraethyl lead is DEATH for a cat.

The Ape Man
08-04-13, 11:44 AM
"Quality" has nothing to do with the problem .

A mid 60s small block Chevy does not use nearly the quality of components as a '68 on Cadillac engine. Factory hardened valves, valve seats, a high nickel content alloy block and many years of design advancements are what people paid for and received. Cadillac was not just another GM product in those days.

08-05-13, 06:53 PM
The 1972 Cadillacs could run on either leaded or unleaded gas. I'd recommend premium unleaded for your car.