Be careful taking your summer ride on a winter spin

Dear Ask a Mechanic,

I own a 2006 Mazda MX-5 Miata that I store in my unheated garage during the winter. I put in a gas stabilizer and use a trickle charger on the battery. Not wanting to leave it for six months, about once every two weeks, usually on a nice day when it is around zero degrees Celsius, I warm up the car and then drive it around the block a few times until it gets to running temperature. I then put it away in the garage again. A friend suggested that, although this is great for the tires, it is not good for the engine. Would it be better to put it up on blocks for the whole six months? - Storage minded

The use of stabilizer in your fuel and a trickle charger to maintain your battery is spot on. When it comes to the trickle charger, just be sure that it’s a maintenance float charger and not a steady “on” low-amp type, as those can overcharge and damage the battery.

Your question is a tough one, as I partly agree with both of you.

A car sitting in one position for six months will flat-spot the tires. The permanence of those flat spots depends on multiple factors, including the temperature during the return to use, and the tires’ compound and construction. Michelin, for one, recommends lifting and supporting the car to take the weight off the tires when it is being storing for a month or more.

Personally, I’m not prepared to do that with my Mazda RX-8 as I need to be able to move it to access things in my garage when I am storing it. Instead, during storage I will add an extra eight psi (pounds of pressure per square inch) to my tire’s specified 32 psi to reduce the flat spotting and compensate for pressure loss from the cold. After hibernation, the resulting flat spots have always worked themselves out after driving around 10 kilometres.

While taking your ride out during the winter to do a couple laps around the neighbourhood can be good for the soul, I am still hesitant about recommending it, especially if your Miata only has summer tires on it. Several makers warn against moving a vehicle fitted with their performance summer tires at temperatures of minus-seven degrees or colder, as it risks permanently damaging them.

Even on a nice, warmer day, there is still salt dust and residue on the roads, so you’re also exposing your car to that. As well there is the moisture in the oil and exhaust systems, which – as your friend noted – a few laps around the block may not be sufficient to burn off.

Insurance is another consideration. It could be a hassle if an incident occurred at near-zero temperatures on summer tires. Sadly, your best bet is to leave your car parked, on stands, if possible.

Ask a Mechanic is written by Brian Early, a Red Seal-certified automotive technician. You can send your questions to wheels@thestar.ca. These answers are for informational purposes only. Please consult a certified mechanic before having any work done to your vehicle.