We know from a thorough reading of the NASA CCR that “glycol-based antifreezes that may cause a slippery condition if spilled on track” aren’t allowed in racecars. We also know that winter in much of the United States is harsh enough that temperatures regularly plunge below freezing.

Those kinds of temperatures do not bode well for a racecar engine block filled with distilled water. That means when winter comes a knocking, it’s time to prepare your racecar for the long, cold offseason. That means winterizing, a subject on which we contacted two experts for their advice on properly servicing and storing racecars over the winter.

Brian Bohlander is the former Great Lakes series leader for Thunder Roadster. He also works for Old World Industries one of the country’s largest manufacturers of engine coolant and other automotive chemicals.

Tony Salloum is the president of VAC Motorsports, a leading parts manufacturer in Philadelphia that specializes in BMW performance parts, service, auto body and collision repair, race fabrication, engine and performance services.

First Things First

If you can swing it, the ideal place to store your racecar is in a heated garage — preferably on jack stands. Short of that, in a regular garage will do and short of that, an enclosed trailer. With each subsequent option, in the order they were presented, the chances of the car being exposed to below freezing temperatures increase greatly.

“I’ve known some people from time to time who actually will put electric heaters overnight inside of a trailer and run them,” Bohlander said. “But that is one option to keep the vehicle or keep the coolant as close to or above freezing as possible. I do know that there are some cases where at the racetrack, where guys will, before they go call it a night, they’ll put a heater inside the trailer for two or three hours. So that way that hopefully by the time you get to early morning that it’s still above freezing that day.”

That can work for winter storage, but a garage is far superior to any kind of trailer, heater or no heater. If you do have to leave a car in a trailer over the winter, put some street tires on it before you put it away.

For race tires, use the same logic you would use for your pet dog: “If you’re cold, they’re cold. Bring them inside.” Race rubber does not react well to temperatures near or below freezing. Just ask 25 Hours of Thunderhill drivers and crew chiefs. They can split in cold temperatures and be rendered useless. They’re too expensive to leave in a cold garage.

Cooling System

Modern internal-combustion-engine cooling systems were designed to be run with glycol-base coolant that doesn’t freeze, but they’re built with fail-safes such as freeze plugs that will pop out if the engine coolant freezes and expands inside the block. That keeps the block from cracking, but even freeze plugs don’t guarantee against cracking entirely.

There are two schools of thought on cooling system prep. One is to empty it completely. The other is to drain, flush and fill it with water and coolant. The safest and surest method is to fill it with water and coolant because you can never be entirely certain you’ve gotten all the water out of a cooling system, which can cause problems that are easily overcome by filling it with water and coolant. That also allows for other winter storage processes we’ll address a bit later.

“Usually what most people do, and what’s highly recommended, is to do what we essentially call a flush and fill. Drain out all the water out of the system, put a 50/50 mix of a glycol-based coolant with water,” Bohlander said. “There’s a couple ways you can get that. You can buy it already done from the manufacturers. Like Peak, for example, all of our products are made in a concentrate and a 50/50 blend. The 50/50 blend, obviously, makes it easier because you don’t have to do any cutting with water. It’s already regulated the way it needs to be to get the maximum freeze protection.

“Not only will it protect the cooling system itself to keep any of the water from turning potentially to ice and pushing out freeze plugs or doing any other internal damage to the engine or radiator cooling system at any point, but it also has the inhibitors in the additive packages that also help lubricate the system and prevent corrosion from happening. So it’s the trifecta there,” he added.


For lubricants, one way to prepare the car for winter storage is to do nothing. Well, almost nothing.

People used to change oil before winter storage only to have to change it again before you get the car ready to go racing again in the spring. Salloum is of the opinion that you need not change the oil before winter storage if the oil in it is relatively fresh. However, he suggests setting the car up so you can start it periodically — once every two to four weeks — and let it warm up.

“You don’t change the oil and then park the car, but it’s also nice to get the moisture out of there. If you can start your car, run your engine occasionally to where you get it to operating engine temps and your oil temperature comes up as well, you actually boil the moisture out of it,” Salloum said. “Because when cars are in storage, you’re still building up moisture.”

The better safe than sorry argument is to put fresh oil in before winter storage and then again before you go racing. However, that does add to the cost of winterizing. Bohlander brought up another good point.

“You don’t want oil that’s been run a bunch. And if it has particulate left in it, what happens with that is that particulate then obviously sits at the bottom of the pan, which can potentially when you start the engine back up in spring get run through the system,” he said. “So ideally before wintertime, you’d want to put a fresher oil in the vehicle, just so that there’s no chance of any particulate that’s in the oil sitting and then getting run back through the engine first part of the year.”

Go with the solution that fits your budget. As alluded to earlier, the only way you can start and run the car over the winter is if you have the cooling system filled with the 50/50 mix.

For gearboxes and differentials, there’s really no good way to get them up to operating temperature during the winter. Sure, you can run the engine with transmission in gear, which will spin transmission and differential, but not in a significant way, and probably not enough to boil off moisture. Make sure you change them both before you go racing in the spring.

Because brake fluid is hydroscopic, it will absorb moisture over the winter, so much so that it also will need to be flushed and changed before you set a wheel on track in the spring.

Electrical System

The electrical system itself doesn’t need any maintenance, but in modern racecars, the battery typically does. Even though you’re going to be starting the engine periodically over the winter, you’re going to want keep the battery charge levels topped off.

“If you’re not going to run your car and you have a gel battery, you’re better off actually putting it on trickle charge because a lot of these more expensive batteries, if they die, they don’t like to come back to life,” Salloum said. “I mean the Odyssey and a lot of these batteries that are really expensive batteries, you’re better off putting a Battery Tender on them and just keeping a trickle charge on it, and that’s a good way to preserve your battery for the winter as well.”

When spring arrives, make sure your connections are tight and clean, then go win races.

Fuel System

The debate over fuel system maintenance for winterization has been vacillating between storing the car with the tank full or completely draining the tank. The problem is that both arguments have merit. On racecars, the difference, and the factor in which method you choose lies with the kind of fuel tank you have.

On the “keep it full” side, the argument goes that when there is an absence of fuel, there is more chance for moisture forming — and for potential corrosion. Obviously, corrosion only occurs in metal fuel tanks, not plastic, but the gathering of moisture over time in a plastic tank also can present problems.

“The more oxygen there is, the more moisture you can actually develop inside the tank, and the more water you can potentially have in your fuel. So if you have more fuel in there and it’s pretty full, then the potential for contamination of the fuel from water from moisture becomes less,” Salloum said. “Having an additive in there never hurts either, so you can absolutely do an additive. Now again, if the temperatures are nice and you’re in a climate controlled garage, then it really doesn’t matter just the fuel stabilizer alone. But I think if you store with a lot of fuel, you’re going to help to prevent the moisture from buildup in the gas tank just due to the same reason you have moisture in the oxygen in the air, and the more air there is in the tank, the more potential moisture you have in your tank.”

Speaking on behalf of the drain-the-tank contingent, Bohlander used to empty the fuel cell on his Thunder Roadster completely, which most likely was because it was a fuel cell, not a gas tank in a production car.

“If a car has a fuel cell or fuel cell bladder in it, the worst thing you can do is have fuel sitting in it. Because the fuel, all that’s doing is deteriorating the bladder and the foam and everything inside of it,” Bohlander said. “In a car that’s got a production tank, it’s not quite so bad.”

Salloum incorporates a lot of checks on the fuel system into the maintenance routine VAC Motorsports performs in the spring, before the cars go back out on track.

“We have seen some situations where the foam deteriorates a little bit sooner. So I guess if you really want to do things the right way, and again, everything is dependent on a budget, but one could say, well, let’s replace the foam every year or every other year inside a fuel cell,” Salloum said. “If you want to be sure that the foam never breaks down and starts to cause blockage and issues. We have seen the foam cells fail. The bladders themselves are going to be good for at least five years.”

Springtime Fitting Out

Salloum outlined that VAC Motorsports starts by replacing all the lubricants, engine, transmission and differential, and brake fluid.

“You do all your fluids, brake fluid, motor oil, diff and transmission because the differential and the transmission, they’re going to have moisture from not moving,” Salloum said. “You can start up your engine in the winter and boil the moisture out, but you can’t do that inside your transmission and differential.”

Next the cooling system gets flushed of the glycol-based coolant and gets replaced with distilled water and the cooling system of your choice, (VP Racing Stay Frosty, Water Wetter, Purple Ice, etc.)

When the fluids are done, Salloum suggested inspecting belts and hoses and any other rubber components that can be affected by cold temperatures. They all must be looked over, and that includes axle boots on rear-wheel-drive cars and especially CV boots on front-drive cars.

Salloum added that a compression check and a leak-down test also are essential preseason maintenance procedures.

“So if a compression and leak down wasn’t done at the end of the season, and even if it was, you’re better off doing one fresh at the beginning of the season. That becomes your baseline for follow-up visits,” Salloum said. “So if you’re trying to do preventive maintenance and you want to see if your valve train or if your oil consumption, rings, whatever, how everything is performing, if you do compression and leak-down tests on a regular basis, then you can kind of get an idea of which direction the engine is going. Just like a blood pressure test will kind of let the doctor know which way your body is going.”

Independent of the usual internal-combustion winterization procedures, racecars require more checks on things like window nets, harnessesw and even driver safety gear such as head and neck supports. Fire systems also need seasonal maintenance.

“For the preseason inspection, we started to talk about fluids and this and that, but part of the preseason inspection for us is making sure all bearings are tight, wheel bearings and joints and control arms,” Salloum added. “And anywhere where there’s a joint or a rubber bushing, making sure everything is secure, making sure drive axle boots are not torn because they also have plastic or rubber on those things. So, anything like that we address before the first event.”

Hopefully, it’s warmed up by then.

Images courtesy of Brett Becker, Jason Wise Photography, VP Racing, Fuel Safe and Larry Chen


  1. If you have access to a lift, I recommend putting the car high up to help keep mice from chewing wires and hoses. If you don’t have a lift, consider placing traps or poison in/around the car.

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