After switching to full synthetic oil (from conventional), I noticed the following:
1) Easier cranking in the winter
2) Engine was quieter
3) During the winter, the engine oil feels much less viscous immediately after moving off.
. Why? What am I missing? .... Does full synthetic really make that much of a difference in the way the engine runs? ...
Synthetics produce less ring deposits, well known for that.
Very true. Many engines that begin to use oil have ring coking. I have seen rings completly seal off with carbon deposits. Synthetic oil will greatly reduce this even with much longer OCIs than dino. Any time you see varnish, which is caused by oil oxidation, coking may become a problem.
For a sound engine, synthetic oils like M1 or PP will give several advantages over dino.