Re: Leaded fuel

Posted by TxGoat On 2023/11/7 17:38:32

Microwelding/valve recession only occurs in higher compression, higher output engines running under heavy load.
It's never been an issue with cars built prior to about 1956, and even those will have no issues if not driven hard, provided the cooling system is in good order, wear is within reason, and the valves are seating correctly with proper valve lash.


Before about 1955, lead levels were low even in "Ethyl" gasoline. Most pre war gasoline had very little lead additive, if any.

All that said, Av gas is fine for old cars, if you can afford it. It's high quality fuel, being stable and free of gum and ethanol.The lower octane versions of AV gas would probably be the best choice. The lead content will do no harm, except perhaps to the exhaust system. Some sources claim that leaded fuel promotes exhaust system decay, especially in lightly-used cars.

I' familiar with the gray goo in 1960s oil pans. I never heard of it being a problem, and it is probably evidence of inadequate oil changes. Gray goo and a light deposit of mahogany colored varnish were often found in older engines of that era.

The next best thing to Avgas would be "Tier 1" pump gas. It's supposed to be more stable than "off brand" gasoline.