I've been doing engine work on my '89 IROC since May of this year, and it's had the same tank of premium gasoline that I had back then (little less than a quarter-tank left). I've heard that it's not good for the gas to be in there that long.

What are the potential problems this could cause and what do I need to do about it?

Thanks

 

Old fuel tends to varnish and gum up.

There's a good chance you'll be okay. I'm not sure 5 or 6 months is long enough to cause bad problems. I'd go ahead and drain the tank and run a fresh tank when it's time to fire up the car. Perhaps some fuel system cleaner mixed in. In most cases fuel system cleaner is a waste of money, but for something like this it's cheap insurance.

 

You should be ok with the gas in the tank..like the last person stated old fuel will gumup and what not. If in doubt throw some cleaner in there.

 

Yeah that's not really long enough to cause trouble, but it wouldn't hurt to throw in some alcohol in case there's any condensation.