On a 2005 Lincoln LS :
D5 is the normal drive position for the best gas mileage . The transmission
will operate in gears 1 through 5
D4 ( overdrive cancelled ) the transmission operates in gears 1 through 4
d5 for lower rpm's, better fuel economy
Normally on a 2006 Lincoln LS you would drive in " D5 " That allows the transmission to use all 5 gears If you are in " D4 " the transmission uses the first 4 gears and doesn't use the overdrive
D5 ( Drive 5 ) is the normal operating position for the best fuel economy ( the transmission operates in all 5 forward gears including overdrive ) D4 ( Drive 4 ) allows the transmission to use the first 4 forward gears , no overdrive . Use that position if you have a heavier load , if you want engine braking etcetera
( 5W-20 ) according to the 2005 Lincoln LS Owner Guide
According to the 2005 Lincoln LS Owner Guide : The 5R55S automatic transmission does not have a dipstick
All Lincoln LS transmissions are sealed. There is no dipstick to check fluid.
108
2005
in the truck, passenger side
timing CHAINS
in the truck by the spare tire compartment
In the trunk next to the spare tires.