I have taken the Extension course on Home Preservation, I also judge 4-H and Open class food preservation. The general recommendation is to use up everything home preserved is within one year. I have used things that have been more than one year.
Anything that is pressure canned as green beans are, you have the risk of botulism. Botulism can be deadly. NEVER taste when you are checking to make sure home canned beans are safe. Check the seals, rust, smell and then if you are still concerned, start boiling them, if they are bad you will be able to tell very quickly from the smell.
People will tell you they open canned (not recommended), used paraffin (not recommended) or took other short cuts and they survived. They were lucky, not everyone is.
The bottom line is do you want to risk your health and your families health by using something that is 6 years old?
Use the adage: if in doubt, throw it out.
PB from MN
who is very picky about canning and food safety