If you’re seeing black stains beneath your vehicle when it’s parked, that oil slick could be caused by a leak in your oil cooler hose. The oil cooler acts as a radiator by cooling the engine oil after it has circulated throughout the engine and heated up. The hose is the method for passing oil through to the oil cooler, and is made from a rubber that will lose necessary cohesion after time.
The lifecycle of an oil cooler hose may be shorter than some other rubber hoses simply because it’s constantly in contact with an incredibly hot substance, and then cools down rapidly when no hot oil is passing through it. Eventually, the part will harden and begin to crack, and then you’ll start to see oil sweat out through the rubber and leaks will occur.
Here are a few pointers that will guide you to the best choice in oil cooler hoses:
Type of oil hose: There are two types of oil cooler hoses: transmission oil cooler lines and engine oil cooler lines.
Transmission oil hose: Transmission oil cooler lines go through the passenger area of a vehicle and are very short – only about 6” long. Transmission fluid will leak red, so that’s a strong indicator that something is wrong with this particular cooler line.
Engine oil hose: Engine oil cooler lines go along the driver’s side of the vehicle and the fluid that comes from them will be either a dark brown or black in color. These cooler hoses are also very short; only about 4-5” in length.
Correct fit: You have to find just the right oil cooler hose to fit your vehicle. Since components are packed so tightly, it’s critical that you make sure the hose is the correct one for your particular car; keeping in mind not only length but also diameter and angle.
OEM specifications: The best oil cooler hoses are built to OEM standards. While an aftermarket part is acceptable, OEM parts are guaranteed to fit and work accurately. Check the part number on your current oil cooler hose and reorder that exact type as they vary by model year, make, and engine size.
It’s always important to double-check the number on the old oil hose against the new part before you install it. Keeping your oil cooler hose in good working condition will ensure your car runs well.
YourMechanic supplies top-quality oil cooler hoses to our certified mobile technicians. We can also install an oil cooler hose that you've purchased. Click here to get a quote and more information on oil cooler hose replacement.
This article originally appeared on YourMechanic.com as How to Buy a Good Quality Oil Cooler Hose (Automatic Transmission) and was authored by Valerie Johnston.