What Is a Rear Main Seal and Why Does It Matter?

June 20, 2025

Your engine has a lot of moving parts, and one small but very important part is called the rear main seal. Most people don’t think about it—until it starts to leak.

Engine's open bottom, revealing pistons, crankshaft, and oil, covered in grease. | Jim Brangham Auto Repair
What Does the Rear Main Seal Do?

The rear main seal is a rubber or silicone ring that seals the back of your engine where it connects to the transmission. It helps keep motor oil from leaking out of the engine. Oil is what keeps all the engine parts moving smoothly, so a leak is a big deal.

Signs You Might Have a Rear Main Seal Leak

  • Rear main seal leaks aren’t always easy to spot, but here are a few signs to look for:
  • Oil spots under the middle or rear of your car
  • Low oil levels even after a fresh oil change
  • A burning oil smell while driving
  • Oil on the underside of your vehicle or near the transmission

If you notice any of these symptoms, it’s best to have your vehicle checked out soon.

Is It a Big Repair?

Yes, replacing a rear main seal is a labor-intensive job. That’s because it sits between the engine and transmission—two large parts that usually need to be separated to get to the seal. But at Jim Brangham Auto Repair in Cathedral City, our experienced technicians know how to get the job done right.

Why You Shouldn’t Ignore It

A leaking rear main seal will only get worse over time. If your engine runs out of oil, it can lead to serious engine damage, and that can be very expensive to fix. Catching the problem early can save you a lot of trouble (and money).

We’re Here to Help

If you think your car might have an oil leak or any other issue, bring it to Jim Brangham Auto Repair. We’ll inspect it, explain what’s going on, and walk you through your repair options.

📍 Located in Cathedral City, CA 📞 Call us today at 760-321-7040 to schedule your visit!
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