Unfortunately, this part is difficult to see and find on a car, and is not designed to be replaced easily. One of the most serious signs is if your oil light comes on shortly after an oil change.

If you are seeing oil accumulating under the car, or noticing you need to top off your oil more frequently than usual despite not using the car more than is typical, you likely have a leak. If your car seems to be losing oil quickly but you do not see visible leakage when your car is parked, your rear main seal could be in the early stages of failure. Let’s examine how to spot a rear main seal malfunction, and what to do next. Excessive heat, old age, high mileage, infrequent use, and worn bearings can also be factors contributing to rear main seal failure. It is also crucial to check your oil and change it as needed, as low oil levels can cause issues with the rear main seal. Using the recommended oil for your car’s engine is a critical step to try to keep your rear main seal functioning the way it should. If this malfunction goes unnoticed, permanent engine damage can occur, which can make the vehicle beyond repair. The reason it is such a costly repair is that replacing it often involves dismantling the transmission and even part of, or all of, the engine. Its primary purpose is to keep oil sealed inside the back of the engine, which is where the crankshaft and the transmission meet. The rear main seal exists in the back of the engine, around the crankshaft. In older vehicles, the cost of this repair is often greater than the actual value of the car. One of the worst things that can happen to a car is a failure of the rear main seal.

5.9 cummins rear main seal leak