鬆O2 sensor，噴 WD-40後， overnight， 用力 238 磅。
Here it suggests to spray it on while the exhaust "is somewhat hot" (and then apply leverage). Some spray it on once an hour for two hours. Some let it sit overnight. Possibly spray it on then turn the engine on, let it heat up, spray it again, cool down, that type of thing, anything to try and help it seep in. Tap it with a ball-peen hammer to try and create some space for the oil to get in. All while spraying and/or trying some leverage on it. You'll want to wire brush it clean as well so the lubricant can get access more easily.
In terms of penetrating oil strength, one study showed this:
No Oil used .................................. 516 pounds
WD-40 ................................... ...... 238 pounds
PB Blaster ................................... .. 214 pounds
Liquid Wrench ................................127 pounds
Kano Kroil ................................... .. 106 pounds
50% ATF - 50% Acetone mix............53 pounds
