I have a BMW cabriolet with interior leather. What's your recommendation about using the manufacturer's BMW UV leather protectant? If I'm driving in Canada with five months of sun every year, do I need it? Will the leather fade in colour if I don't?– Simon
Even in Canada, if you're driving with the top down, sunscreen for your leather seats might seem like a no-grainer, er, brainer.
Our skin needs sunscreen. Leather is skin. Therefore, it needs sunscreen. Right?
Maybe. I haven't yet found research that compares leather conditioners and shows how well – or if – they prevent fading.
BMW's lotion isn't the only product with ingredients meant to protect the finished layer of leather from the sun, says Centennial College professor Paulo Santos.
"From the research I've done, most leather cleaners and conditioners have ultraviolet inhibitors to help prevent fading," Santos says.
Even without evidence of how well conditioners protect from UV rays, Santos recommends using a leather conditioner on seats to help the leather maintain its moisture.
"Leather is basically a thicker type of skin which will dry up, shrink, become hard, and eventually crack," he says. "Leather will need protection to keep its original texture."
But using too much conditioner too often can cause more harm than good – many vehicle manufacturers recommend regular vacuuming and, when needed, a wipe with a barely damp cloth.
I sent your question to BMW and hadn't received answer by my deadline.
Santos says all vehicles need extra protection – inside and out – during the summer heat.
"Extreme heat and UV rays cause the finish and interior materials to break down," he says. "Temperatures can change as much as 15 to 20 degrees within 12 hours – this repetitive expansion and contraction adds to the toll on your vehicle."
Santos recommends using shades on the inside of the glass to help protect interiors and Carnauba paste wax to protect the paint.
Without added protection, the clear coat that protects the coloured paint layer underneath will break down from sunlight, he says.
"Carnauba will protect the paint from the UV rays and seems to stay on the paint the longest when compared to some other types," he says. "You can almost compare Carnauba wax to a sunscreen used to protect our skin when exposed to direct sunlight."
If you have any repair or maintenance queries for Jason, send him a message at firstname.lastname@example.org or contact him through Twitter: @JasonTchir