You all seem to be such proficient chefs. Well here is a place to share some of that cooking knowledge. Or do you have a cooking problem? Ask away. Jams and chutneys go here too.
We always use second hand jam jars, providing the lids have a pop-up centre and the seal looks intact.
So far we have had no problems keeping tomato puree type sauces for well over a year, and have been doing it for yonks.
Our Kilner jars are too precious for sauce and they are used for bottled fruit ... plums, goosegogs etc.
Tony
Disclaimer: I almost certainly haven't a clue what I'm talking about.