Synthetic oils do tend to be a little expensive.
Don't see why it would not be ok to fire up your engine. It's not so much a question of how long the oil has been sitting in the engine. It's a question of oil break down due to heat, junk in the oil, etc... You may want to spray a little fogging oil into the cylinders and turn it over a few before actually firing it up just to make sure there is some lubrication .
Jim was doing a study on the Amsoil as to how long he could use it between oil changes without serious breakdown, but ran into (literally) some set backs in his research. Sorry Jim!!!
The synthetics do seem to help with heat build up and tend to require less oil changes (as far as my understaning).
I did use Kendall oil in the old stock car. Don't recall any oil related issues. The few problems were likely due to engine builder (me) errors.
Here is a link to way more than you likely want to know about oil:
http://motorcycleinfo.calsci.com/Oils1.htmlSteve