But how do you point a spot light up when you're parked in a snowbank :) easy to slide the box underneath the oil pan. 
Oil pan heaters work better than you'd imagine given the "fin" issue. 

Jeff in balmy Winnipeg (-2c!)

Sent from my iPhone

> On Jan 2, 2016, at 12:35 PM, David Beierl <dbeierl@attglobal.net> wrote:
> 
> At 11:51 AM 1/2/2016, Jeff Palmer wrote:
>> I've made a little box with aluminum foil and a 100w bulb. You'd be surprised how much heat that produces.
>> Jeff
> 
> Around 350 BTU/hr if all the visible light gets turned into heat.  Your basic 1500 watt electric heater makes about 5200 BTU/hr.  A heat lamp bulb doesn't waste much as visible, and has a built-in reflector.  I think they might be 150 watt.  And I've used a halogen work light to remove microprocessor sockets with a couple hundred pins from a circuit board.
> 
> Yrs,
> d