Automatic transmission with Jake's going down the hill

2000 -2100 max engine braking rpm

 

The new Detroits and DT12 transmission you don't need to use the service brakes at all going down most grades. Someone posted it was good for 8% grade holding back 80,000 lbs from what I've seen that's spot on. Really good jake's on these modern detroits with autos is an understatement...

 

It's an automatic with more programming and sensors than the space shuttle to the moon. I figure when it's in automatic mode and I hit the Jake's on max and it goes to 2100rpm it knows what it's doing and I let it. Only time I manually shift is when going up a hill and it wants to upshift and runs the rpm super low I'll throw it in manual and downshift. Super low rpm at full power will kill an engine way faster than 1500-2000 rpm

 

In auto, is there an economy and performance mode? Our freightliners jake differently in each mode.