Classic/Antique Car Repair: unleaded gas, gas additives, desert don

Question
How do older cars run on todays unleaded gas? What has to be done to a 60's era car to burn todays gas?

Answer
They run fine, in normal collector type driving.  There will be slightly less power, and slightly poorer gas mileage, but generally, you don't notice it at all.  The one thing that you have to be aware of is that if the car is driven hard, in high temperature conditions, especially if you are towing a trailer and driving fast, you will have somewhat faster wear of the exhaust valve seats, because the heads were not designed for unleaded gas.   But if all you do is drive the car at normal highway speeds, and don't live in the Sahara desert, don't worry about it at all.  When the time comes to rebuild the engine, tell the machine shop to put in hardened seats in the exhaust valves, and you'll not have to worry about unleaded gas effects again.  

The different manufacturers began using hardened seats at various times as leaded gas was known to be going away - Chrysler corp had all hardened seats by sometime in the early 70s, for instance - so it matters which brand and year of car you are asking about.  

But regardless of all that, the horror stories about engine damage due to unleaded gas are pure hype - trying to get you to pay money for uneeded gas additives (which don't help at all, or at least not that anyone has been able to measure carefully) or to rush down to your machinist get get your valve seats changed.   Just drive your car, and be aware that when and if you ever need a valve job, consider whether or not to throw in an addition $500 to get the hardened seats installed at that time.  

Dick