Why would it state to only use it below -10 degrees? If it gets below freezing I would plug my truck in. It's not a must, but why make your engine work like that?

 

Anyone concerned about power consumption should get themselves a programable timer. I run mine from midnight 'till I leave around 4:30 am.

 

When I used to have my scangauge plugged into my truck I found I needed to have the block heater on for 3 hours minimum to warm it up (looking at coolant temperature). Colder and I would leave it on longer. My timer messed up though so last night I left it plugged in all night. It'll start fine cold, but why not have a little heat when it's 16 degrees out .

 

I realized my post was off topic so:

#1) How can I tell it's working? No idiot light does not make it ewasy to see if the thing actually works.

I have never heard a noise or sizzling, but you can use a cord with a light on the end to make sure it has power to that point.

#2) Is it ok to keep plugged in all night? I have to use a 50' outdoor extension chord (14 gauge).

Yes it is ok to do that. A timer would be better. I used to have it set to go on for 3 hours.

3) Any particualr testing methods to use to check operation?

Not sure, but you could get a scangauge and if the coolant temp is warmer than ambient you know it's working. I remember it being 80-110 degrees depending on ambient. Maybe a lighted cord to make sure power is getting to plug.

Mark