Piston Slap: Are Racing Oils Good For Vehicles Made Before 1975

For clarity's sake, this discussion focuses on vehicles made before 1975 that do not have catalytic converters and likely have a flat-tappet camshaft. Adding racing oil to a vehicle with catalysts can destroy them, and newer, roller-tappet camshaft motors rarely need racing oils!

Rod writes:

I am in the process of purchasing a 1957 dual-quad, 283-cubic-inch Corvette and would like to understand the best oil to use. (Weight, type, etc.) I live in central Florida, if that matters.

Sajeev answers:

There's a lot to unpack in Rod's question, so bear with me as I go through everything.

Considering this Corvette has dual quads (that could be a lot of fuel for a 283 small-block!), I wonder if the rest of the motor is similarly modified. I'd ask the seller if the motor still has a flat-tappet camshaft, or if the engine was also upgraded to a roller cam. A roller-camshaft motor has much less friction and can run modern oils designed for street cars. It's only the older, flat-tappet camshaft motors that need a higher zinc content (ZDDP) to give them extra protection against wear.

There's another factor to consider: Most older vehicles are not driven daily, and all modern oils are shockingly competent in their design. So don't fret about it, as any oil (in the correct weight) will ensure an antique's motor outlasts its next five owners at the mileage levels we inflict upon it. Still, we might have found the best option for these applications-from a name most folks trust-and it's readily available, too.

In a Piston Slap from February, we discussed the oil choices available for cars made before the advent of the catalytic converter, and Hagerty Community member hyperv6 likely gave the best advice. He noted that Mobil 1 Racing oils have way more zinc than other formulations. I went to their website to verify, and he's right. Wow.

And hyperv6 went further, suggesting Mobil 1 Racing oils are readily available at places like Walmart and come in a variety of weights. He recommended 15w40 weight oil for that previous question (about a 1974 Corvette). I'm inclined to think that's ideal for Rob's 1957 Corvette, too. But don't take my word for it; here are the details about Racing oils from Mobil 1's own website:

Mobil 1 Racing oils are formulated with anti‐wear (zinc/phosphorus) chemistries at twice the level of automotive street oils to provide enhanced protection of highly loaded valve train systems found in some race engines. Based on the high level of anti‐wear chemistries, Mobil 1 Racing oils are not recommended for street use.

That last sentence is true, as most cars these days have catalytic converters and roller camshafts. But for this 1957 Corvette, I reckon hyperv6's sage advice rings true. Walmart lists all the weight sizes of Mobil 1 racing oils available, so I'd recommend starting your search there.

Best of luck with the purchase, Rod. And what say you, Hagerty Community?