If you’re wondering how to tell if your rear main seal is leaking, then your vehicle must be leaking something. Before we get into the technical details of determining if you’ve got a rear main seal leak versus another type of oil leak, we need to be sure that it is indeed oil that your vehicle is leaking, not power steering fluid or transmission fluid or some other type of lubricant. To be sure you’ve got an oil leak, try checking out our article on how to determine what your car is leaking.
Once you’re sure you’ve got an oil leak, we can help you figure out whether it is the rear main seal that is leaking or some other oil seal or gasket in your engine.
How to Tell If Your Rear Main Seal Is Leaking
- Are there any higher oil leaks?
- Are there drips from the bell housing?
- Is the oil pan gasket leaking?
- Is the flywheel or flexplate oily?
Since rear main seal leaks are uncommon on most vehicles it’s very possible that you’ve got another leak higher up on the motor that is dripping down and just looks like a rear main seal leak. The most common leaks that can masquerade as a rear main seal leak is a valve cover gasket leak, intake manifold gasket leak or a distributor gasket leak. If you find oil on your engine above the bellhousing, check for leaks at these locations. If you find one, repair it, clean the engine and check for leaks again in a few hundred miles.
A rear main seal leak will cause oil to drip from the bottom of the bellhousing at the front of the transmission. If you have drips coming from in front of the bellhousing, locate those leaks, stop them and clean the engine. After a few hundred miles you can check again for leaks to see if you still have any.
The most common leak that is confused as a rear main seal leak is an oil pan gasket leak at the rear of the engine. The oil pan gasket is just below the rear main seal. An oil pan gasket is also usually much less expensive to replace so it’s important to check for leaks in your oil pan gasket before you jump to any conclusions.
The best way to prove that you’ve got a rear main seal leak is the check if the engine side of the flexplate or flywheel is oily. If the rear main seal is leaking on your engine it will drip oil onto the flexplate or flywheel and sling oil around the bellhousing. Most engines have an inspection cover in the bellhousing the allow you to check for this. If you find oil on your flywheel or flexplate, use BlueDevil Rear Main Sealer to restore your rear main seal and stop your leak.
You can find 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 Distributor
- DYK Automotive
- Fisher Auto Parts stores
- Auto Plus Auto Parts stores
- Hovis Auto & Truck Supply stores
- Salvo Auto Parts
- Advantage Auto Stores
- Genuine Auto Parts stores
- Bond Auto Parts stores
- Tidewater Fleet Supply
- Bumper to Bumper Auto Parts
- Any Part Auto Parts
- Consumer Auto Parts
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leak_repair,jpg – By Welcomia – Licensed by Getty Images – Original Link
BlueDevil Products can be found on Amazon.com or at AutoZone, Advance Auto Parts, O’Reilly Auto Parts, NAPA, and other major auto parts retailers.
64 responses to "How to Tell If Your Rear Main Seal Is Leaking"
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I notice my car has small leak after driving it but does not continue to leak when it just sits for days, does the rear main only leak when crankshaft is spinning or will it drip when car is not run also..although I did not get car on a lift but I can see it dripping down between bellhousing and flywheel inspection plate area.
Al-
Based on your description, we recommend using 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 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. You should expect to start seeing results after approximately 100-200 miles of driving.
Thank you!
-BDP
Can I put both products (BlueDevil Oil Stop Leak and Rear Main Sealer) in the oil fill at the same time to cover both possibilities? I have a drip that is steady coming from the area if the main rear seal but at stated, it’s pretty hard to tell. Please let me know soon. Thanks.
John-
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!
-BDP
I have a 2004 GMC Sonoma I am leaking like a half of quart of oil everytime I stop a puddle forms but quits when I shit off engine this is very expensive and oil is all over bottom of truck can’t tell if rear main or not seems like no oil above but not 1000 % would Blue Devil work if it is main seal?
Robert-
Thank you for asking about your GMC Sonoma. If you are not 100% sure where the leak is coming from, the best product to use would be 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.
Unfortunately, it sounds as though you may be losing oil a little too quickly for the BlueDevil to be successful. The product is intended for leaks that are seeping or lightly dripping. Replacing the offending seal/gasket may be your best option.
Thank you!
-BDP
So I add the whole bottle??
Lance-
One bottle of the BlueDevil Rear Main Sealer would treat up to 8 quarts of oil. You would use one oz. of the product per quart of oil.
Thank you!
-BDP
Hello. I have a 2014 Civic Exl CVT with 47k. I recently noticed an oil leak that I’m almost sure is coming from behind the torque converter inspection cover. I can’t find any leak sources above that plate. I haven’t removed it yet. Here’s links to 2 pics that show the leak areas and where oil accumulates. Should I assume a rear seal and get sealer for that, or start with the other sealer you sell? Thanks
https://ibb.co/cx34rpK
https://ibb.co/DKCgwgy
Nate-
Thank you for asking about your Honda Civic. If you’re not 100% sure where the leak is coming from, the BlueDevil Oil Stop Leak would be the best product to use. This would treat any of the rubber seals/gaskets throughout the oil system, whereas the Rear Main Sealer would specifically treat the rear main seal. You should expect to start seeing results after 100-200 miles of driving.
Thank you!
-BDP
I have a duramax diesel leaking it holds 10 qts of oil I put 2 bottles of rear main seal still leaking can I add the oil stop leak on top of that
John-
Roughly how many miles have you driven since adding the Rear Main Sealer? Is the leak coming from the rear main seal or are you unsure? Please contact our technical support line at 888-863-0426 so that we can get a little better understanding of the vehicle’s condition and be able to make any appropriate recommendations.
Thank you!
-BDP
Will injector cleaner damage what blue devil has already fixed I didn’t want to put injector cleaner in there until I asked. It’s been months since I put the blue devil on I just want to put the injector cleaner in now
Hunter-
Using the injector cleaner will not undo the seal that BlueDevil created. Once the product seals, it would be a permanent seal, so you should be good to go at this point.
Thank you!
-BDP
Hi, I have a 2006 Impala. I had a small leak. Oil was on my oil pain, and when my car set, I had a few small oil spots on the passenger side, under the oil pan. The blue devil sealer, actually sealed whatever seal was worn because I no longer see oil spots under my car, on the passenger side. However, I still have oil leaking out. Oil, be leaking on my oil pan and my oil level will decrease over time, gradually. Now, does this mean I need to change the oil pan, along with oil pan gasket? Basically, is that the problem I am experiencing, now?
Conrad-
Thank you for asking about your Chevy Impala. Based on your description, it is possible you were dealing with multiple leaks. The fact that you noticed some kind of improvement is definitely a good sign. When was the BlueDevil added? Please contact our technical support line at 888-863-0426 so that we can get a little more information about the vehicle and be able to further assist you.
Thank you!
-BDP
I have a 2006 GMC Yukon she’s been a great car but has been leaking oil for sometime now at least over a year. I recently took it to a mechanic shop they told me it was the rear main seal. She has 275,000 miles on her they said even if I did do everything I needed to do there was no guarantee that the seal would stay sealed . If that’s the case I don’t feel like spending $1000 unless I know it’s going to be Fixable . Thanks
Rhonda-
Thank you for asking about your GMC Yukon. Based on your description, it may be worth trying the BlueDevil Rear Main Sealer before opting for the expensive repair. As long as the leak isn’t more than seeping or lightly dripping, you would be a good candidate for the product.
Thank you!
-BDP
I have an 02 ford f250 thought my pedistal was leaking rebuilt my turbo an replaced the o rings to my pedistal seems oil leak hasnt stopped how many bottles of the rear maine sealer do I add to see if it stops my oil leak
Bert-
Thank you for asking about your Ford F-250. One 8 oz. bottle of BlueDevil Rear Main Sealer would treat up to 8 quarts of oil. As long as the leak isn’t larger than a seep or light drip, you would be a good candidate for the product. You should expect to see results after approximately 100-200 miles of driving.
Thank you!
-BDP
My 97 Honda manual transmission got caught in a down our that flooded the roads. I pretty much had to plow though a lake. I made it home 2 blocks away, and found all the oil drained out. It seems to be right around the oil pan, but there was splatter slightly above the pan gasket, on the filter, and on the opposite side of the pan. Did I knock my pan gasket, rear main seal, or something else loose?
Jeffrey-
Thank you for asking about your Honda. Based on your description, it is definitely possible that running the vehicle through that much water played a role in your oil loss. It sounds as though it would be coming from the oil pan gasket, as that is where you are noticing the splatter.
How quickly are you losing oil? Have you attempted to refill the oil since this occurred? Please contact our technical support line at 888-863-0426 so that we can get a little better understanding of the vehicle’s condition and be able to make any appropriate recommendations.
Thank you!
-BDP
I have a 2000 Jeep Wrangler TJ 4.0 with roughly 145k miles on it.
There’s a engin oil drip at the bottom of the bell housing of the transmission. It’s not a constant drip, but after being parked for 24 hours on concrete, there’s about a tea spoon of oil on the pavement. I cannot tell where the leak is comming from.
Please Advise,
Thanks,
-Jay
Jay-
Thank you for asking about your Jeep Wrangler. Based on your description, we recommend using the BlueDevil Oil Stop Leak. The Oil Stop Leak is a universal application, and would be able to treat leaking oil pan gaskets, valve cover seal, rear main seal, etc. If you are not 100% sure where the leak is coming from, the Oil Stop Leak would be your best bet. Feel free to contact our technical support line at 888-863-0426 with any other questions.
Thank you!
-BDP
I have a 2008 Chrysler 300 2.7 that i just rebuilt and have a oil leak. Its not a really bad one, but i end up with a couple of spots on the floor in the garage.
I’m leaning towards rear main seal that in new as well. My question is will the blue Devil product help me with a new seal?
thanks looking forward to a fast response.
Eric-
Thank you for asking about your Chrysler 300. BlueDevil is intended to revitalize and recondition old/shrunken rubber seals back to their original state and flexibility. It does not harden or thicken in anyway, so it would not fill a void or plug in a gap. Unfortunately, it would not have an affect on a newer seal.
Thank you!
-BDP
So a friend noticed an oil leak on my 01 tiburon in his driveway. I quickly diagnosed it as a failed crimp seam on the filter. I added an extra qt of oil so I could make it home because it was leaking pretty good while running. Now that I’ve changed the oil and filter, my car will leak from the flywheel housing just enough to mark its territory only after I’ve run the car. It takes 15-20 minutes to start a puddle but then stops one cooled…I checked my oil and it is past the full mark. Can correcting the fill level and adding stop leak fix my issue?
James-
Thank you for asking about your Hyundai Tiburon. Based on your description, we recommend using the BlueDevil Oil Stop Leak to stop the leaks you are experiencing. You would want to drain some oil to get it back to the proper level. You should expect to start seeing results after approximately 100-200 miles of driving.
Thank you!
-BDP
I have a 07′ Chevy Tahoe 4×4, I have replaced the rear main seal twice. But it is still leaking. the vehicle has over 200,000 miles, I have replaced the oil pan gasket while i was replacing the rear main. but now its leaking more. I used a Dorman rear main part fro Oreillys any help
Johnny-
Thank you for asking about your Chevy Tahoe. Is the leak still coming from the oil pan gasket and the rear main seal? Is it possible that the leak is coming from a different seal/gasket? If so, the BlueDevil Oil Stop Leak is great at revitalizing and reconditioning rubber seals/gaskets. It does not harden or thicken in anyway, so it will not plug in a hole or fill in a gap. It is 100% safe to use. Feel free to contact our technical support line at 888-863-0426 with any questions.
Thank you!
-BDP
I have a very fast leak coming from above the front side of the trans and the back of the engine. I mean it pours out fast. I was driving and my oil pressure went from normal to 0. And the whole undercarriage is soaked with oil. I’m not sure where it’s leaking from though. Can anyone help?
Ky-
Based on your description and the extremity of the leak, it would be best to have the vehicle brought into a certified ASE mechanic for a hard part repair.
Thank you!
-BDP
I have driven two hundred miles in my Jeep and I am still getting oil dripping from the bell housing. Can I use stop a leak?
Chris-
Yes, the BlueDevil Oil Stop Leak would be able to treat the leak you’ve described. You should expect to start seeing results after 100-200 miles of driving.
Thank you!
-BDP
I have a 2008 Chevy Silverado .. 5.3 lit. Oil pouring out between oil pan and bell housing .. I’m told the rest main seal will not pour out like that and it’s probably a gasket from oil pan near rear main seal ..
Jerry-
Thank you for asking about your Chevy Silverado. The BlueDevil Oil Stop Leak is intended for leaks that are seeping or lightly dripping. Based on your description, you may be losing oil a little too quickly for the product to be able to seal. Replacing the gasket may be your best option.
Thank you!
-BDP
I have an 04 jaguar xj8 with 68k miles on it ihave an oil leak somehere in pass side when car in parked in an inclined position i notice a lot of oil when parked on a level surface it is minimal . How much oil stop leak should i use given the car takes 7.5 qts of oil
Luis-
Thank you for asking about your Jaguar XJ8. One bottle of the BlueDevil Oil Stop Leak would be sufficient for your 7.5 quarts of oil. You should expect to start seeing improvement after 100-200 miles of driving.
Thank you!
-BDP
i replace my rear main cranck seal with a new victor reinze seal, after replacing it still leaks but not like the first time. what will you recommended please help
Andre-
The BlueDevil Oil Stop Leak would be the recommended product for a rear crank shaft seal leak. You should expect to start seeing results after 100-200 miles of driving.
Thank you!
-BDP
I notice you keep saying you need to drive 100-200 miles to see results. Would that be continual driving that distance without stopping or can you do start and stop driving over several days? Thanks
Mark-
It does not have to be a continuous drive. You are fine to drive the vehicle 5, 10 mile intervals, here and there. Drive the vehicle like you normally would. Just keep in mind it will be around 100-200 miles of driving before you start to see improvement.
Thank you!
-BDP
I have a 2009 GMC Sierra I just took it to a mechanic and he put some dye in it but before they put the dye in it he was saying something about the rear main seal but I just drove it to Gatlinburg which is about 5 and a half hrs from me and I was 870 miles due for an oil change and only lost a quart of oil in all that the leak is not real bad yet it’s just a small small leak right now what can I do to stop the oil leak without having to replace anything right now?
Chad-
Thank you for asking about your GMC Sierra. The best product to use for your rear main seal leak is the BlueDevil Rear Main Sealer. You should expect to start seeing results after 100-200 miles of driving. Feel free to contact our technical support line at 888-863-0426 with any other questions.
Thank you!
-BDP
I have a 2002 Chevy tahoe and everytime I park it in my driveway and get in it the next day it has a oil spot on the concrete when I looked underneath it I can see it dripping around the plug and oil filter and it slings on my exhaust what could that be
Tyler-
Thank you for asking about your Chevy Tahoe. Based on your description, you would be a good candidate for the BlueDevil Oil Stop Leak. The product is intended to treat leaks coming from rubber seals/gaskets. You should expect to start seeing results after approximately 100-200 miles of driving.
Thank you!
-BDP
I have a 2007 Chevy Impala and have been told that I have approximately 5 leaks in my oil pan seal. And of course they tried to say that my front and rear main both need to be replaced. My father always warned me that if your oil pan is leaking 9 out of 10 your front and rear means are not leaking they just have overflow oil from the oil pan. I lose about a quart between oil changes. My dash oil light comes on and goes off comes on and goes off etc. And my oil pressure light comes on all the time. What do you suggest and is your product something that you think I could rely on to help with this issue. Very little oil droplets on the ground, no oil around the valve covers, and no black smoke from exhaust. And if I use your product and I end up having to replace the oil pan seal will it cause any problems by using your product first. And using your product first will that let me know whether my feels need to be replaced?
Susan-
Thank you for asking about your Chevy Impala. Based on your description, we recommend using the BlueDevil Oil Stop Leak. The product is 100% safe and compatible to use in your vehicle. The product works by revitalizing/reconditioning rubber seals/gaskets. The product does not harden or thicken in anyway, so it would not deter you from replacing parts in the future. You should expect to start seeing results after 100-200 miles of driving.
Thank you!
-BDP
I have a 2001 Chevy Tahoe that lost all oil pressure. There is a sever leak that is coming around what looks to be the driver side close to the transmission pan which is odd. My dad thinks that it may be the rear main seal. What do you think it could be? The bottom of the oil pan and transmission is covered in oil. Do you think that your product will help with this?
David-
Thank you for asking about your Chevy Tahoe. Based on your description, it sounds as though the vehicle is losing oil a little too quickly for the BlueDevil to be effective. The product is intended for leaks that are seeping or lightly dripping. A hard part repair may be your best option.
Thank you!
-BDP
2005 Nissan Altima, I changed the oil about a week and a half ago. Two days ago the oil lamp came back on and the oil was basically gone. Without digging too deep I see the oil is on the back side of the engine block, burning smell. I was referred saying it could be a rear engine leak. Will that product seal the issue ? Or am I dealing with a bigger issue since it leaked so quick? The was no puddle underneath the car.
Bryce-
Thank you for asking about your Nissan Altima. If you are not 100% sure where the leak is coming from, the best product to use would be the BlueDevil Oil Stop Leak. The product is intended for leaks that are seeping or lightly dripping. Based on your description, you may be losing oil a little too quickly for the product to be successful. However, the product is safe to use, and may be worth given a try, depending on your situation.
Thank you!
-BDP
2001 camry had an engine clean oil was above oil pan area only drips after running while driving bad oil smell thru heater and when I stop oil smell gets worse valve cover gasket replaced. When leaks left of oil pan from front view
Gene-
Thank you for asking about your Toyota Camry. Based on your description, we recommend using the BlueDevil Oil Stop Leak. The product is intended for leaks that are seeping or lightly dripping, so it sounds as though you would be a good candidate for the product. You should expect to start seeing results after 100-200 miles of driving.
Thank you!
-BDP
I have a 2012 Nissan Altima it has a oil leak but it’s on the driver side at the top not the bottom. I got new valve cover gaskets cleaned the oil off n drove it again and I see more oil. So it wasn’t the valve so what else could it be?
Moranda-
Thank you for asking about your Nissan Altima. Unfortunately, it would be difficult to say exactly where the leak is coming from. If you are not 100% sure where the leak is coming from, we recommend using the BlueDevil Oil Stop Leak. The Oil Stop Leak is a universal application and would be able to treat leaking oil pan gaskets, valve cover gaskets, rear main seals, etc. You should expect to start seeing results after 100-200 miles of driving.
Thank you!
-BDP
2008 rav4 4wd 2.4L.100 miles . slight oil leak at the bottom of the bell housing, looks like motor oil. it never drips on drive way for the past 19 month I owned the car. I opened the black plastic cover where the the fly wheel is and visually inspected it and inserted my finger to check if there was any oil but was completely dry. What do you think it is?
Daniel-
Thank you for asking about your Toyota Rav4. Based on your description, you are most likely dealing with a rear main seal leak. A rear main seal leak will often results in oil leaks being found at the bottom of the bellhousing. We recommend using the BlueDevil Rear Main Sealer for your leak. You should expect to see results after 100-200 miles of driving.
Thank you!
-BDP
I have a 2007 dodge caravan and I just had my Cad converter replaced but was told my oil seals where not sealing 100% so the check Engine light comes on saying it not filtering completely
Will that oil help my situation.
Dee-
Thank you for asking about your Dodge Caravan. The BlueDevil Oil Stop Leak would work best in this situation, as it would treat any of the rubber seals/gaskets throughout the system. Whereas the Rear Main Sealer would only be treating the rear main seal. Hope this helps!
Thank you!
-BDP
I have a 1990 Honda Accord and replaced the valve cover gasket after oil leaks caused misfiring, plugs and wires. There was another small leak on the front driver’s side. I noticed tiny droplets in my garage which grew into a bigger leak from that area. I was told replace timing seals, main seal, and valve cover gasket and when they do that they do the timing belt and water pump. Big job. Which would likely be the leak causing a leak from the front driver’s side? I have oil all over my garage and worse in front. When I park places, I see the oil leak from the front. Which would be causing this leak and how do I tell? Can I do the worse leak first ? And, is it necessary to do the timing belt at this point?
I gather that BlueDevil Oil Stop Leak would not help at this point.
Thank you for your answer
Audrey
Audrey-
Thank you for asking about your Honda Accord. How quickly are you losing oil? Please contact our technical support line at 888-863-0426 so that we can get a little better understanding of the vehicle’s condition and be able to make any appropriate recommendations.
Thank you!
-BDP
I have an 07 Chevy Silverado with the vortex max, it has 218,000 miles an about every 2 weeks I have 2 put about 2 quarts in it, it is leaking about the oil filter somewhere, I can’t see leak anywhere under the hood or anywhere else, would your product be helpful or do I have bigger issues?
Cody-
Thank you for asking about your Chevy Silverado. It does sound like you are losing quite a bit of oil. It would be best to have the vehicle looked at by a certified ASE mechanic to diagnose where the leak is coming from. From there, you can decide on repair/replacement or other alternatives.
Thank you!
-BDP