Fixing a Rear Main Seal Leak

Rear Main SealHaving a leaking rear main seal can cause a lot of problems with your car.  Like any oil leak, a rear main seal leak will leave your car and your driveway a sticky oily mess.  If you’ve got an older car or an oil stained driveway already, it may seem like it’s not that big of a deal to allow your rear main seal to continue to leak, however, there can be some significant side effects of a leaky rear main seal.

First, your rear main seal is the lowest seal in your engine compartment.  That means if it begins to leak it will allow oil to leak more quickly than from any other seal in your vehicle. The other problem with having a leak this low on your engine is that it can mask indications from other leaks that you may have higher in your engine.  You may have multiple problems lurking in your engine, but a rear main seal leak will make them difficult to detect.

Another problem with a rear main seal leak is that it can go from a drip to a flood in a matter of miles.  A rear main seal may start leaking simply due to old age, a small crack or because the seal is getting stretched out.  Any of these problems can cause a slow leak, but they also can quickly turn into a large leak.  A small tear or crack can quickly turn into a large one due to the rotation of your crankshaft inside the seal.  A stretched seal also can tear easily as the seal gets deformed and thin.

All of these problems are so dangerous because they can quickly lead to a low oil level in your engine.  A low oil level is dangerous for 2 reasons.  First, your pistons and piston rods are lubricated by the oil in your oil pan splashing as the crankshaft spins.  If you’ve got a low oil level in your oil pan these components will receive inadequate lubricating which will accelerate wear.  Second, if you have a low oil level in your engine it can lead to low oil pressure due to the oil pump becoming uncovered.  Low oil pressure can cause a variety of problems like a lack of lubrication to your main bearings, your camshaft bearings or your valves.  This again will cause accelerated wear of these components.

Replacing your rear main seal will most likely be a very challenging job.  Replacing the rear main seal on your engine will require removing your transmission and most likely removing your engine from the car.  No matter what kind of vehicle you drive, removing the engine and transmission from it will most likely be an extremely expensive endeavor.

If you’re looking into fixing a rear main seal, then you’re on track to save a lot of money and headache.  Fixing the rear main seal that’s already installed in your vehicle rather than replacing it can save you the time and labor of removing your engine and transmission.

To fix your rear main seal, pick up a bottle of BlueDevil Rear Main Sealer.  BlueDevil Rear Main Sealer is specially formulated to restore the cracked, shrunken and leaking seal that is your vehicle to its original size, shape and sealing ability.

To learn more about how BlueDevil Rear Main Sealer works, click on the banner below!
BlueDevil Rear Main Sealer

You can also purchase BlueDevil Rear Main Sealer at any of our partnering local auto parts stores like:

  • AutoZone
  • Advance Auto Parts
  • Bennett Auto Supply
  • CarQuest Auto parts
  • NAPA Auto Parts
  • O’Reilly Auto Parts
  • Pep Boys
  • Fast Track
  • Bumper to Bumper Auto Parts Specialists
  • S&E Quick Lube Distributer
  • DYK Automotive


Pictures Provided By:

rear_main_seal.jpg – By Coddy – Licensed by Thinkstock Photos – Original Link

12 responses to “Fixing a Rear Main Seal Leak

    1. Phillip-

      Yes, BlueDevil Rear Main Sealer will work to stop your axle leak. You should add 1 ounce of BlueDevil per every 1 quart of fluid capacity. You will not need the full bottle for this application. Expect to start seeing results after about 100 miles of driving.

      Thank you!


    1. Brian-

      Thank you for asking about your Ford F-150. The BlueDevil Oil Stop Leak is intended for leaks that are seeping or lightly dripping. If you are losing oil too quickly, replacing the seals may be your best option.

      Thank you!


  1. What is the difference in Blue Devil Oil Stop Leak and Blue Devil Main Seal. My bottle looks different than the rounded bottle and does not say Main Seal? Is it just an updated bottle?>

    1. D Rice-

      BlueDevil Oil Stop Leak is more concentrated and is the universal application that will work for various leaks such as oil pan leaks, rear main leaks, valve cover gasket leaks, etc. Whereas the Rear Main Sealer is specifically formulated for only a leaking rear main seal. If you are not 100% sure where the vehicle is leaking or there seem to be multiple leaks then we recommend using BlueDevil Oil Stop Leak. It is not necessary to add both products simultaneously.

      Thank you!


  2. Hi
    I just have a quick question, it seems my SUV is leaking by the rear main seal so I am thinking in using your product, the SUV is almost due for a oil change (200 miles) so should I use your product before or after oil change or it does not may any difference?
    I really appreciate your help on this matter.

    1. NDM-

      Based on your description, we’d recommend changing the oil first and adding the BlueDevil Rear Main Sealer to your fresh, clean oil. The product can stay in the oil for the life of the oil.

      Thank you!


  3. Good day, I am driving a chevy spark light 2010 800cc engin. Was at garage this morning with a oil leak and it seems like the main rear crank shaft seal this is after I have fixed the front seal last year June.
    Can I use the Blue Devil Rear Main Sealer for this or do I need to use the Blue Devil Oil Stop Leak?

    1. Jackie-

      Thank you for asking about your Chevy Spark. The best product to use for your crank shaft seal leak is the BlueDevil Oil Stop Leak. BlueDevil Oil Stop Leak is more concentrated and is the universal application that will work for various leaks such as oil pan leaks, rear main leaks, valve cover gasket leaks, etc. Whereas the Rear Main Sealer is less concentrated and specifically formulated exclusively for leaking rear main seals.

      Thank you!


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