Hi,

I have an oil sump heater, dealer installed, and a battery heater, my
install. For $14 the battery warmer guarantees a start regardless of
temps/oil weight.  The oil block heater thins out the cold oil nicely and
engine spins over well. At $45 for the block heater I'd go with the battery
warmer first. Way easier to install too. Use 5W30 in -20-30F weather.  A
fully warmed battery gives ample juice to spin the starter AND wake up the
FI brain.  A cold battery may spin you albeit sluggishly, but below about 7
volts the FI brain stays asleep.  NO go.  fine for carb'd engines. Tim