I have posted this information in the "What did you do to your 4th gen Legacy today? thread as well.
I'm going to post this information in a separate thread as well as in here in hopes that it will help some of the people that are having cylinder misfire issues.
To add to my post above (sorry for being long winded but after I keep reading all of the "cylinder misfire" issues that keep popping up, it makes me wonder if, in a lot of cases, the issue lies here) I forgot to mention that the same holds true with dielectric grease on various electrical plugs and ESPECIALLY on spark plugs.
It's very easy to become overzealous with dielectric grease on spark plug boots. Because they fit very snugly on the plug and cause a seal against outside elements, even more than a film can cause the plug boot to be hydraulically pushed back off of the porcelain area of the spark plug, which immediately disconnects the plug from the clip and causes driveability issues. In some cases, it only pushes the boot back a little bit and the spark can jump across the gap and the engine still runs smoothly but under strain, it exhibits a misfire and in a lot of cases, people change the plugs, add a bunch more dielectric grease to the boots, have the same issue again, and can't figure out the problem.
On LGT, we don't actually have the plug WIRE/BOOT issue but we can easily do the same thing with the coil packs. Too much grease inside of the coil pack boot can cause it to hydraulically separate the coil pack clip from the plug, even slightly, and then find that you have cylinder misfire codes at the least, and at the worst strip out the bolt holes that hold the coils in place. I also absolutely recommend the use of dielectric on the coil harness plugs too, but in a VERY tiny amount. Just a smear across the female pins is plenty. When you plug your harness into the coil pack, it will force the grease down into the female receptacle and coat the metal parts and that ALL you need.
The best way to use dielectric grease is VERY sparingly. For some reason, many people believe that dielectric grease is there to help carry the current through the connection. This is absolutely NOT true. Common sense tells you that if the grease carried current, what would happen when you put dielectric grease on a 60 pin connector? It would immediately short all of the pins together and that would NOT be any fun at all-the magic smoke would come out of the computer and it wouldn't work any more (computers are just empty metal boxes filled with magic smoke and once the smoke comes out of the box, they don't work anymore...
) and that gets EXPENSIVE.
use anti seize on ANY electrical connection as anti seize DOES carry current due to the metal flakes suspended in the grease. The ONLY exception is if you are in a VERY wet climate, such as marine applications, you can use anti seize on the battery terminal connections AT
the battery ONLY
as it will help protect against salt water corrosion.
Hope this will help everyone with misfire issues.