Conversion from loop plugs (where less than half of the heat produced by the circuit goes into the prechamber) to pencil plugs (where 80-90+% of the heat is concentrated in the prechamber) WILL improve cold weather starting by almost 10 deg F. Changing to a full synthetic oil (likr Mobil 1) will also improve things about another 10 deg. F. but I don't know if these two different results are entirely additive. I have only tried the oil change myself (none of my cars have series/loop plugs).

I know of many people that have done the glow plug conversion and they all report vastly improved cold weather starting - changing it from a constant challange with every start to ALMOST fun, until temps get below zero (F).

Marshall