I don't quite know what you mean with squiffy but my bf had an 86 that he regularly drove without oil, no problems. He had a fucked radiator and it would puke out all the water in no time, so he just kept some bottled water with him and filled it up once the check engine light came on, no engine problems. He actually tried to kill it once, put it up on stands and let it run forever without oil and it wouldn't die. It ran out of gas instead. I forget what else he did but one thing is for sure, he shit kicked that car...
My 88 threw a couple of belts and you didn't even know until you got home, my electric fan failed once and it would overheat on a regular basis, no problems after it got fixed. Right now it has a bad oil leak, the tranny is fucked, the electrical is messed up, the under carriage I don't even wanna look at (I lost my muffler the other day, lol).... yet it still drives relatively fine if you ignore the obvious tranny issue.
The only thing that really sucks with 300zxs is the electrical. And as usual rust if you are living in a rainy part of the world.