Upshifting
For normal acceleration and cruising, Mazda recommends these shift points:

*1 Always observe local speed limit regulations.
Downshifting
When you must slow down in heavy traffic or on a steep upgrade, downshift before the engine starts to overwork. This gives better acceleration when you need more speed.
On a steep downgrade, downshifting helps maintain safe speed and prolongs brake life.
Shift Gear (Shifting) Speed Limit
Direct ModeMazda 6 Owners Manual: Range of topics
This manual contains procedures for performing all required service
operations. The procedures are divided into the following five basic
operations:
Removal/Installation
Disassembly/Assembly
Replacement
Inspection
Adjustment
Simple operations which can be perf ...
Mazda 6 Owners Manual: Starter removal/installation
Warning
When the battery cables are connected, touching the vehicle body with starter
terminal B will generate sparks. This can cause personal injury, fire, and
damage to the electrical components. Always disconnect the battery negative
cables before performing the following operation.
1. Di ...