It would be technically better to heat the block (faster transfer of heat), but, the oil would cause the most problems with cold startups (viscosity/wear), next would be coolant (unless mixed for the temps), then the pigiron. Since your providing heat to an enclosed system, I find the dipstick method to be the least intrusive as the plug heater is replacing a nonwear part with a wear part. I like the work light method, but would limit it to 2 hours before starting (as eventually the excess heat would get wicked away).

 

I grew up in Alberta Canada where the temp got down do -30. Sometimes as cold as -43 deg Celsius. The best thing I found other than a garage to park in, was a block heater. Anything that heats or circulates the fluids in the block is a good idea.

My aunt and uncle do the same, they live in the North West territories up near Alaska, were even the bears freeze there nuts off lol.

 

lol Poor bears, Speakin of, Small Black bear in pasture reminded Mrs Newbie of 10 million ways to die and the treehugger chaning himself to a tree protestin loggin? Seems Mr Bear happened along and saved the treehuger from having freezin nuts. ROFl

 

the only problem i ever had starting my truck in below 0 temps is the gas freezing up...never had problems cold starting. it does seem a little slow when the wind chills get lower but other than that its good. if it did get to be a hassle starting in the cold i'd just push it in the garage and wait about an hour(LP tank and heater do wonders here).

 

I do not think it is gasoline freezing on you (gas starts to solidify around -95 degrees farenheit), but perhaps water that has not mixed with ethanol. Also, wind chill does not apply to vehicle temp (with regard to starting).