Go to http://www.med.umn.edu:8853/misc/archives/Files/
and check out the article on the Dometic fridge, it's useful and well
written. My '87 Syncro's fridge has been lit for 12 days now with the
burners used for cooking a few times only. Others I've asked have
reported being surprised at how long their propane lasts. Sorry this
isn't more definitive but I'll let this group know when mine finally
runs out. Thanks for the replies concerning my Syncro's desire for 
a 5 spd(now it wants a bigger motor too! arggg...)
I'll keep you posted,
Jay