Oil Leaking Under Parked Car

Oil is typically dark brown to black and feels slick between your fingers, and it tends to leave a spot roughly under the front-middle of the engine. Transmission fluid is usually reddish and often shows up further back. Coolant tends to be thinner, sometimes green, orange, or pink depending on the type, with a faintly sweet smell. If you're not sure, a paper towel test — dabbing the spot and looking at the color — is an easy way to check before your visit.

A small, slow leak that isn't dropping your oil level much is usually fine to drive on for a while, as long as you keep an eye on the level between now and your appointment. A leak that's noticeably lowering your oil level, or one that comes with a low-oil warning light, is more urgent — running low on oil can cause real engine damage, so that combination shouldn't wait.

If you've spotted a leak and haven't had it diagnosed yet, checking the dipstick every week or two, and topping off if it's low, is a reasonable stopgap until you can get it looked at. It won't fix the underlying leak, but it keeps you from accidentally running the engine low on oil in the meantime.

It depends on the source. A gasket that's just starting to weep can stay mild for a long time, while a worn seal or a loose drain plug can get gradually worse. Since it's hard to tell which one you're dealing with just by looking underneath the car, having it diagnosed gives you a real answer instead of a guess about whether it'll hold or worsen.