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?
69 302 rebuilt 10 years ago by a shop with a more performance reputation (347 stroker, bored out a bit, other speed parts). Builder was an older fellow and insisted the engine use 20W50. When other, younger mechanics heard about this they were surprised “that’s diesel oil” and other comments.
It lands pretty good on your Mobil chart, gets labelled as V-twin aka motorcycle oil. For me locally, this formulation is now only stocked on shelves as “motorcycle oil” but this only happened in the last few years. Everything I dug into research wise basically agreed that it is just “old school high good additives any vehicle oil”.
But absolutely do not use it in a vehicle with cats.
It’s labeled as V-Twin oil because that’s the grade oil that Harley has been specifying with their air-cooled motors for ages and the Mobil 1 oil was made to match Harley’s requirements. It may be suitable for other uses, but it was intended for Harley V-Twins.
I’ve never done it myself (for the reasons mentioned above) but I have heard of a lot of people running Rotella 15W40 Diesel oil in older engines. I just looked up the zinc content at 1150 ppm and its right in the pack with Mobil 1
If in doubt about anything on this contact Mobil 1 and thre can make recommendations.
The no street on racing oils has to fob with the converters in many cases. Even if it would damage a converter over time it is cheaper and easier to replace than a cam.
In the case of the 283 duel quad I expect it is the factory set up which works fine. The Mobil should be fine but you can confirm with Mobil with one Email.
As for Rotella use care as not all Rotella oils are high in zink.
Reading web sites and contacting companies is very important. Also keep up and confirm the oils find not change.
“Reading web sites and contacting companies is very important. Also keep up and confirm the oils find not change.”
+1 to all this
From the data sheet for Valvoline VR-1 20W50 Racing Oil, Zinc is 1400ppm and Phosphorous is 1300ppm. It’s also available at auto parts stores. I use VR-1 20W50 and Mobil-1 15W50 depending on application.
I use the Shell Rotella T4 in 15W40 weight in all my older engines. It has 1200ppm of zinc and has worked of me for years an years and 50,000 miles in several engines. I also like the Delvac 130 line of diesel oils. There is also Lines of Hot Rod oils from Lucas, or Driven, or Brad Penn etc, that are specifically made for older engines and those with flat tappet cams needing high zinc etc additives.
I also use Rotella 15w40 in my older gas engines and haven’t had any issues. I should start buying it by the barrel since I also use it for a diesel tractor and a diesel 7.3 that hold 15 qts.
I have used Rotella with success – had it on hand for the Yanmar diesel, and am currently using Castrol GTX Classic 20-50 in my ’63 mini again looking for high zinc….. Both play nice with the transmission too….
Speedway Motors has excellent tech articles on high zinc motor oils and also a complete list of high zinc oils. Also a lot of other excellent tech articles on various other aspects of our hobby. I highly recommend their website.
It would have been nice to offer a comparison chart with Valvoline’s VR-1 racing oil in standard and synthetic, which state “ZINC” boldly on the bottles. I use Mobil I in my diesel truck and Kia SUV, but VRI standard in a 1955 Pontiac Chieftain and a 1963 Porsche 356 B. I would immediately change my loyalty if I was sure Mobil 1 was really superior in it’s zinc content.
Valvoline VR1 Racing Oil 1300ppm zinc, Shell Rotello 1 diesel oil 1450ppm zinc, Mobil Racing synthetic 1850ppm zinc.
It is more than just the ZDDP, the additive package matters a lot too. Especially if the car sits for a long time.
Too much ZDDP can be corrosive as well.
The biggest issue with oil weight is the hydrodynamic wedge of lubrication and the resistance to engine forces shearing that wedge. If you have a stock oil pump a 20w-50 or worse straight 30 oil might be too heavy. A diesel oil has a different additive pack intended for diesel fuel contamination vs gasoline.
If your oil pressure is low and your bearing clearance or diameter is large, like say with a Buick 455, a 10w-40 oil is likely going to give the best performance. It is application specific. I’ve run Mobil 15w-50 with a converter truck for 24 years and I run it in a hydraulic roller small block 383. I run Amsoil in the boosted Gen 4 LS, and 5W-40 Mobil 1 FS in all (new) Hemis.
I run 20w-50 VR1 too, but it shouldn’t be left in in there for long periods. I change every 6 months and have had no issues.
Hope that helps
For flat tapped engines it is important to have a minimum of 1200ppm zinc, this is to protect the camshaft and cam followers (tappets) I use Penrite oil that we purchase in Canada by Sports Car Centre in Edmonton,
They are the only ones that are selling these oils, they have the biggest assortment of classic car oils in Canada and I know they will ship to the US as well.
I’ve been running Mobile 1 15/50W motor oil formulated for flat tappet engines for 10 years in my 66 El Camino big block 396 with great performance and no trouble. The engine has a mild cam and stiffer than stock valve springs. It’s great not to have to use a zinc phos additive with each oil change. It’s readily available at Walmart for a great price.
Reccomended weight oil for a ‘78 350 engine in my ‘78 Chev Blazer. Engine is stepped up a bit with cam and high comp piston. Currently runs very good, few miles per year.