Oil is the lifeblood of your engine. Keep it cool, keep it clean and keep your engine running at peak performance. Oil technologies have changed since the big block in your 1966 Impala rolled off the assembly line in Flint. The motor might be the same 396ci but the pistons and the rings certainly are not the same as they were over 40 years ago.
Rebuilt or freshened original engines deserve special handling when it comes to break-in oil. Rotella is easily available and relatively inexpensive. Rotella, manufactured by the Shell Oil Company, has higher zinc dialkyldithiophosphate content than most standard oils. The zinc content is important in break-in oil providing protection for unexpected metal to metal contact. Amsoil and Royal Purple are two other high quality oils designed with performance engines in mind.
Once past the 500-mile oil change during break in of a rebuilt or new performance engine, using synthetic oil will protect the engine going forward. Using synthetic oil in an original engine may, at first thought, sound like a great plan but an original engine is not tight enough to handle the fluidity of synthetic oil. Blow-by, leaks and seepage are likely when changing to synthetic oil after 30 or 40 years of conventional oil in the high performance engine of a muscle car.
Choosing heavier weight oil for a high performance original engine is not necessarily the answer either. An original engine that has not been rebuilt should be handled like a fine wine, gently and with respect when it comes to lubrication. High quality oil with a higher zinc percentage will not only protect the engine today but studies have shown that some high quality oils such as Royal Purple and Valvoline MaxLife actually repair cam bearing damage.
A prime example of this level of protection was a situation where the head gasket was breached in a Chevrolet 350 with less than four hours on a fresh motor. Coolant entered the combustion chamber and was blowing out the tail pipe. The engine was lubricated with Royal Purple and ran less than two minutes after the significant breach. The cam bearings were completely smooth and not scored in any way. The cylinders showed no signs of damage. The heads did not warp even with a sudden increase in engine temperature. The aftermarket engine oil cooler kept the oil cool. Upon tearing the engine down the camshaft was not damaged and the only repair required was cleaning and pressure testing the heads and replacing the blown head gasket. Thousands of dollars of potential engine damage was prevented by the use of high quality oil.
The few dollars you might save on less expensive oil is not worth the risk to your muscle car motor. Synthetic oil will not only protect your hot rod motor but will provide better performance. Torque will improve in average to mid-range compression engines. Gas mileage has been shown to improve in some limited studies. The bottom line is protecting your vintage automobile and its engine. Enjoy them as often and as long as possible. High performance engines are not limited to American muscle cars. Germany has been producing performance engines for as many years as there has been American muscle. Porsche, Ferrari and Audi cars for sale are beginning to have some of the mystique carried by the more conventionally labeled muscle cars. Whether American, German, or Italian, protecting your baby`s engine with high quality oil developed for performance engines is the biggest bang for your hot rod bucks.