More Aggressive Techniques (Use with Caution):
* Impact Driver: This is your next best bet. An impact driver, sometimes called a "power bit driver," applies forceful rotational impacts instead of continuous torque. This can break loose incredibly stubborn fasteners. Use a high-quality impact driver bit that fits the plug precisely to avoid stripping the plug or the surrounding metal. Important: Use a strong impact driver with the right amount of force. Too much can damage the differential case.
* Impact Wrench (with caution!): A small, powerful impact wrench *might* work, but it's risky. The force could easily strip the plug or damage the differential case. If you use an impact wrench, use the lowest setting and proceed very slowly. Protect the surrounding area from damage.
* Extraction Tool: If the plug is severely rounded off, you might need an extraction tool. These come in various styles, including screw extractors that bite into the plug and allow you to turn it out. This is a more advanced technique and requires care to avoid further damage.
* Drill (Last Resort): Drilling out the plug should be the absolute last resort. If you choose this route, use a drill press for accuracy. Drill slowly and carefully, using a drill bit slightly smaller than the plug's diameter. You might be able to use a left-handed drill bit to reverse-drill out a broken bolt. Once the plug is out you'll need to replace it.
Critical Considerations:
* Proper Socket: Make absolutely sure you are using the correct size and type of socket (metric, likely). A slightly oversized or improperly fitting socket will round the plug, making removal even harder.
* Protect the Surrounding Area: Cover any sensitive areas near the differential with rags or masking tape to prevent scratching or damage.
* Penetrating Oil Time: Give the penetrating oil ample time to soak into the threads. Multiple applications over several hours or even overnight can make a significant difference. Try different types (PB Blaster, Kroil, etc.).
* Heat Application: If you use heat again, apply it evenly to avoid warping the differential case.
* Professional Help: If you've exhausted all other options, consider taking your Trailblazer to a mechanic. They have the tools and expertise to handle this situation safely and efficiently. It will likely cost less than a damaged differential.
After Removal:
Once the plug is out, clean the threads thoroughly, and install a new fill plug. Use a torque wrench to tighten it to the manufacturer's specification to avoid stripping the new plug.
Remember safety first! Wear safety glasses and gloves throughout the process. If you are uncomfortable with any of these techniques, seek professional help. A damaged differential case is a far more expensive repair than a stuck fill plug.
