Blue Devil Rear Main Sealer is a leak repair additive designed to stop or reduce oil leaks coming from a vehicle’s rear main seal and other engine seals. Many users report positive results, claiming it helps seal minor leaks without the need for an expensive repair. However, its effectiveness largely depends on the severity of the leak, condition of the seal, and how the product is used.
How Does Blue Devil Rear Main Sealer Work?
Blue Devil Rear Main Sealer works by:
- Reconditioning and softening the rear main seal and other rubber seals and gaskets.
- Restoring the seal’s flexibility, allowing it to expand and fill small gaps where oil might be leaking.
It’s a chemical additive you pour directly into your engine’s oil crankcase, where it mixes with the oil and works as the engine runs.
When Does Blue Devil Rear Main Sealer Work Best?
Works Best For:
- Small leaks caused by dried-out, shrunken, or hardened seals.
- Vehicles with older seals that have become brittle over time.
- Situations where the leak isn’t causing a major loss of oil or damage to engine components.
May Not Work If:
- The seal is torn, cracked, or mechanically damaged.
- There’s a large or gushing oil leak.
- There’s severe engine wear beyond the rear main seal.
In these cases, a mechanical repair or seal replacement is the only long-term solution.
How Long Does Blue Devil Rear Main Sealer Take to Work?
- Typically, you should drive 100 to 200 miles after adding it to notice improvement.
- Some users report seeing results sooner, while others may take longer depending on the leak’s size and condition.
How to Use Blue Devil Rear Main Sealer
- Check oil level and top it off if needed (don’t overfill).
- Add the correct amount of Blue Devil Rear Main Sealer to your engine oil.
- Usually, one 8 oz bottle treats up to 8 quarts of oil.
- Drive normally to allow the product to circulate and condition the seals.
Common User Feedback
- Positive reviews highlight its success in sealing minor leaks, saving money on costly repairs.
- Mixed reviews suggest it’s a temporary fix, especially if the problem is more severe.
- Some users see no change if the seal is beyond chemical repair.
Is Blue Devil Rear Main Sealer a Permanent Fix?
No, it’s generally considered a temporary or short-term solution. It may slow or stop leaks for a period of time, but if your seal is severely damaged or the leak returns, a mechanical repair is necessary.
Final Answer
Blue Devil Rear Main Sealer can work, particularly on minor rear main seal leaks caused by aging seals. It’s an affordable option to try before committing to an expensive seal replacement. However, it’s not a guaranteed or permanent fix, and it won’t work if the seal is cracked, torn, or severely damaged. Always monitor oil levels after using it, and consult a mechanic if leaks persist.
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