1998 Toyota 4Runner Owners Manual - Page 152
1998 Toyota 4Runner Manual
Page 152 highlights
4RUNNER (1998) Steel wheels Aluminum wheels The A.D.D. can be engaged or disengaged by the shifting operations described in "(c) Shifting procedure". You should drive in four- wheel drive for at least 16 km (10 miles) each month. This will assure that the front drive components are lubricated.