Understanding Coolant, Oil Needs, and Tire Selection for Classic Vehicles

Dan writes:

Good morning Sajeev,

1. I'm in the process of a double engine swap, transferring a good engine into a good car while the less optimal car will receive the lesser engine. With this swap, I have a lot of fluid replacement to tackle. Specifically, I'm curious about coolant. One engine is a small block Chevy (SBC) consisting mostly of iron, excluding the intake manifold, while the other is a ZZ3 SBC with aluminum heads and intake, both supported by aluminum radiators. Which type of coolant should I use? Does the composition of the engine dictate which coolant is appropriate?
2. How can you accurately determine the oil capacity for an engine? It seems straightforward, but if the dipstick tubes have been altered and there's uncertainty regarding the oil pan, it complicates matters. Given these are Gen 1 SBCs, I assumed 5 quarts and marked the dipsticks, but now with the engines out, my judgment feels questionable.
3. I've got four vintage cars featuring 15-inch and 16-inch wheels. A few years back, I had to replace the tires, and although the tread was barely worn, they had aged out. Nowadays, I prefer to buy used tires, but 15- and 16-inch tires are becoming increasingly rare. What's the most common wheel diameter for passenger cars utilizing a 5″ x 4.75″ and a 5″ x 5″ bolt pattern?

Sajeev answers:

Great questions! Let’s tackle them one by one:

Choosing the Right Coolant

Your choice of coolant should primarily align with what's outlined in your vehicle's owner manual. However, for crate motors like yours, reaching out to the manufacturer, in this case, GM Performance, is often the quickest path to obtain accurate specifications. Engine materials do play a role in coolant selection, particularly with traditional cast iron engines and brass radiators, which typically require the conventional green coolant known as Inorganic Acid Technology (IAT). In contrast, aluminum components require a better-suited coolant, such as Organic Acid Technology (OAT). GM's Dex-Cool is an example of an OAT coolant.

It’s critical to avoid mixing OAT with non-OAT coolants, as this can lead to significant problems, as indicated by reports of issues surrounding Dex-Cool. Furthermore, there's a category of coolant known as Hybrid Organic Acid Technology (HOAT), which can be mixed with various other types of coolant. European engines often use a modified Si-OAT blend. Both of your SBCs can utilize OAT (or HOAT) to minimize confusion in your garage. It may even be wise to consider using the same coolant across your vehicles — but be sure to thoroughly research compatibility before making the transition. Don’t forget to flush out any IAT coolant from components like your heater core if you decide to switch.

Determining Oil Capacity

The oil capacity is usually dictated by the specifications of your oil pan. For instance, if you're dealing with a dry sump system, the total oil capacity will depend on the plumbing configuration and the tank size. Current GM documentation suggests that the ZZ3 engine is compatible with a 5-quart oil pan, and it also comes with a designated dipstick for accurate measurement. If the GM specifications don’t match your setup, identifying the stamped part numbers on your components will be your next step.

Online resources or a quick call to suppliers like JEGS or Summit Racing can ease your concerns if you can’t decipher the specifics. An inspection camera could also be useful to avoid unnecessary removal of the oil pan. Mismatched oil pan and dipstick components can cause considerable engine issues; therefore, engaging with small-block Chevy forums or consulting local engine experts is advisable to secure accurate information.

Navigating Tire Preservation

Currently, both 17- and 18-inch tires are widely available and affordable, with plenty of aftermarket options that can enhance the aesthetics of your vintage cars. If you're inclined to buy used tires, platforms like Facebook Marketplace or Craigslist often have good deals, especially for retro wheel sets fitting your bolt patterns. However, keep in mind that moving to larger wheels, while offering more tire options, can considerably alter the ride and handling characteristics of classic vehicles.

If you decide on tires aged out from the last decade, you might find that they still provide solid wet and dry traction, although their highway noise can be an indication that replacement is necessary in the near future. Modern tire compounds have greatly improved in resisting UV damage, and longevity tends to increase when stored in a garage away from sun exposure. If bigger wheels are a practical solution for you, I recommend aiming for 17-inch options for their balance of availability and performance on the road.

With these answers, I hope you're on a better path with your questions. The Hagerty community's feedback in the comments could also provide more insights or corrections. What do you think, fellow enthusiasts?

If you have a question for Piston Slap, feel free to reach out at [email protected] — providing as much detail as possible will help us assist you better! Keep in mind this is a weekly column, so if you need a faster response, don’t hesitate to mention it in your email.

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