I do check the bolts and screws on all my engines, and when new right out of the box. Only engines I have owned that required the blue goo were the LAs. For some reason the ones I had loosened up the head screws after the first run or two so I just got into the habit of the lock tite. That was the only problem I ever had with an LA. When people say under powered they are comparing the LAs with the FX and AX engines. It's true but it doesn't mean the LAs are dogs. I built 8 Up-Roars and all were powered with the ,46 LA engines. Unless I ran out of fuel I can't recall ever having a dead stick with one. They no longewr make the .40, I never saw a reason for them anyway but I have aquired a couple of them when I was given trainers. The .40 compared to the .46 really is a dog!!