Ok, im about to do a valve adjustment on my car and general rule of thumb is "you never re-use a gasket". but my question is, will it be ok to reuse my valve cover gasket or should i replace it? the gasket has about 77K on it, but i plan on replacing most gaskets at about 90K. so i will be using it only for about 13K or so...

 

You'll be fine. That one is okay to re-use until it actually starts leaking. I think last time I put some liquid gasket in the corners for a little extra insurance.

 

this is one of the few gaskets I re-use quite a bit, I cant be buying new ones everytime i change my valve cover

I havent had a problem yet with re-using the stock one

 

I dont know...you could reuse it but if it starts leaking oil (in the spark plug chamber), or on the outside..then you know its time to replace it. I've been replacing mine every 30+k miles just because I keep taking off my valve cover, getting new valve covers, changing cams, valve adjustments, etc.