Heat affects the whole hardware, not just the cartridge. The battery can expand slightly, and pressure inside the tank can build up. That pressure pushes oil into the coil even when you're not drawing. This is why you might see a drop of oil on the mouthpiece after leaving your vape in a warm car. The fix isn't just airflow, it's also storage. Keep the device upright and out of direct sun.

If you take your vape outdoors in summer, don't leave it on a dashboard or in a pocket. A small insulated bag can help.