When to plug in an engine block heater

The ‘gel point’ for straight #2 diesel, should be well below zero Fahrenheit. The ‘cloud point’ should be a few degrees above zero.

 

Why not ask your coworkers what they did last year? Or company policy for that matter?

 

The block heater doesn’t do anything to keep your fuel from gelling. All it does is warm the engine oil enough to make it easier to start.

I usually plug my truck in any time it gets below 20 degrees F. But mostly that’s just because I am a wuss in my old age and I like it to warm up faster lol.

 

It’s not the gelling I was worried about, but the engine oil. Extremely cold engine oil doesn’t want to flow and the engine clanks and rattles as if it’s going to blow apart.

 

Not to mention tearing up the starter. I always plugged in 20F or colder..

 

Diesel engine I'd plug in at 32°F or colder. A gas engine I'll leave it until it gets around 10°F or colder.

As was mentioned already, you're not heating fuel, you're heating the engine block with a heater element submerged in a water jacket on the engine. You'll get minimal heat into the oil so if you own the bus, I'd consult the manual and use the oil grade recommended for the ambient temperature you see most often. If its not your bus, just plug it in and don't worry about it.

 

2016 more then likely has a cummins ISB. Good cold weather starters. I plug ours in about -2C, 26f.
They start easier, but its not necessary.
They will start unassisted at -20c, -5f ish but sounds like it's falling apart.
Having the correct oil for cold starts is important.
Almost the same engine as in dodge trucks.