Recommended time for block heater
 

Is there an ideal length of time to plug in the block heater?

1 hr

2 hrs

3 hrs?????

temperature dependent?

I have mine set on a timer for 3hrs.
I live in Iowa, so the winter nights are consistently in the low teens to
below zero.

In Ga. I would think 1hr would be plenty if you get down in the low 20's F.

1 hour doesn't seem to make a difference.

2 hours really helps.

3 hours is like a summer day.

You need a block heater in Athens GA? Maybe the Discovery Channel is right a new Ice Age is upon us.... I've found about 3 to 4 hours does it.

in the low teen and single digits of the last couple weeks i had the wifes plugged in and timed to start at 4 am then she started it no prob aro 645am.

That's exactly the same way I run mine. Same results.

I run mine 2-3 hours. I have a timer that I set for about 3 hours before I expect to leave. It also depends on how hard your car is to start, I don't really need to plug mine in I just do to reduce wear and get heat faster.

But anything over 3 hours seems like overkill.

I take my advice from Joe Walsh, it gets plugged in "All Night Long" ;)

no fancy timers or getting up at 2am to plug the car in :D

yup...when I have plugged mine in, it was for "all night long".

Not that it gets that cold down here, but it was in the 30's/low 40's and I was using 20w50 oil, and I am only a few hundred yards from a 50mph road. I wanted to be sure the engine was pre-warmed/warmed enough to have to deal with all those things first thing in the morning.
Besides that, there was heat right away too. (yeah, one gets "soft" after a few years in Fla. and 40° will make your teeth chatter)

On 40 degree days I open my sunroof this time of year and enjoy the warmth. :D

my sunroof only opens when its warm out, not because I choose too, because its got a problem I haven't gotten around to fixing yet ;)

My 82 coupe doesn't have a block heater, my 87 300D and 78 240D both do. Ever since flushing and switching the coupe to Mobil 1 0w-40 synthetic, It starts just as well in welldiggers-you-know-what weather as the other cars that have has the block heater to warm them up, although it still takes longer for me to get heat inside :o

I haven't had to use my block heater since there was snow on the ground...never had starting problems though...just there to help out the engine when its in the 20-30's....the NW is just known for rain and lots of it.
WHen its anything above 50 out, the sunroof comes open..lest its raining.
My drivers window is on the fritz...the sunroof its the next closest thing to my head that actually opens... :D

Answer:
 

At -18F or lower, mine is left on all night.
Above -18F it is not used at all.

More than 4 hrs. you get no additional heating benefits. Just a bigger electrical bill.

Phil

When I recently rebuilt the top end of by new SD, I put a block heater in. It was nice to have a toasty warm block to work with outside.

However, this car is so easy to start. Heck, I've started it easily at 10 deg WITHOUT GLOWPLUGS!

My other SD won't easily start below 10 deg without the block heater.