If you're flooring it at 70mph, you should not be in overdrive.

If you're *cruising* at 70mph, *only* then should you be in overdrive.

OD is not equal to MTX 5th gear. It is a torque convertor and gear setting that maximizes fuel efficiency on the freeway (holding a steady speed between 45 and 85mph) and nothing more. If you're racing, OD should be OFF. If you're below 45, OD should be OFF. If you're above 90mph, OD should be OFF.

Racing in OD and driving around on the streets in OD will burn your tranny out faster.