Jim,
If the cupboard hinges / support straps are made from plastic - then the only suitable lubricant is (as Gary says) Silicone maintenance spray.
Never use WD40 on plastic (or rubber) it's a material similar to paraffin oil and causes plastic to swell - and that will only make the squeaks worse. The same is true of Vaseline - it's not compatible with plastic.
If the hinges / support straps are plated metal - then Silicone spray will still be good, WD40 may work (but will soon evaporate and the problem will return), or a very light smear of Vaseline on the contact points will work long term.
Overall - a can of Silicone maintenance spray (under