Usually, oil leaks are pretty easy to spot thanks to the telltale traces they leave on the garage floor, parking lots and your shop floor, a telltale sign when shopping for used cars and cheap engines. However, there are times when you might encounter a customer’s whose car has low oil but no puddles are being left behind after being parked.

Put It in The Air

This should be common sense, but it bears mentioning. If your customer’s talking about having low oil and you verify that this condition is accurate, put that car on a lift and get it in the air. If you’re running a small shop (or you’re new to the mechanic world and haven’t been able to invest in a vehicle lift yet), this is harder to do. You need to get fully underneath the car. Many leaks are tough to spot if you’re not right under them. You also need to make sure you have plenty of light to see what’s going on.

If a car isn’t leaving puddles behind but is low on oil, chances are very good that the oil is being blown back from the engine during driving. Look at the underside of the car for oil blowing back from the oil pain gasket or from the rear main seal. In some instances, the oil can be blown back in a thin layer that only coats the bottom of the car, rather than dripping down to the floor.

Burning

While it’s possible there’s evidence of an oil leak under the car but not dripping to the floor, the most common issue here is burning oil. All engines burn oil to a certain extent, and most manufacturers state that the loss of a quart or less of oil over the course of 3,000 miles or so is “normal”. However, if there’s more than that lost, you’ll need to look into why the engine is burning so much. Piston rings and seals are the most common issues – these can be replaced during an engine rebuild, but if the engine is particularly old or high mileage, replacing it with a salvage engine or a remanufactured engine might be the better choice for your customer.

Verify the Situation Leading to the Loss

It’s also important to understand that if the customer is doing their own oil changes, they might be the real reason for oil loss (or perceived loss). For instance, if they’re changing the oil and then checking the level before doing a pressure test (when the oil filter gets filled), they’ll see what appears to be low oil afterward. Double check what the customer is doing before anything else.