I just got my new injectors and I want to install them today as it will be the only chance I can do it in the daylight. I didn't order the gaskets ahead of time b/c I thought I'd be able to just buy them the day I did it and every local place has to special order them. I've read they are reusable. Is it true that they are reusable? Should I use some permatex on my old gaskets?