I have a 1998 toyota sienna (240k) and replaced the rear (very difficult) and front (easy) valve cover and put everything back 6 days ago. I noticed yesterday the I used permatex 81343 (gray) anti-seize instead of my Permatex gray gasket sealant!!! I also remove 4 half moons (2 front and 2 rear) used the anti seize. I had driven it for over 300 miles with NO leaks at all and pretty surprised it is holding up. I posted in siennachat and they recommend monitoring for oil loss because honestly, I hate to redo the rear again. What is your opinion in this situation? Would the anti seize work too or should I redo everything again?