Mike,
Of course Bosch wants you to change it every 60k. The reason the light comes on to change the sensor every 30k is part of the Federal clean air requirment. The law required the sensor be changed automatically at 30k with instructions to remove the bulb on early models. I go along with Larry on leaving it alone with a slight modification. The sensor could get lazy and respond slowly which might not trigger the MIL (malfunction indicator light), but reduce performance. In fact if you have a Federal car, you almost have to cut the sensor wire to trigger the light. The early OBD I systems wouldn't trigger the light for any other system failure except on California models. You can check for a lazy sensor with a lambda tester without replacing if it checks out ok.

Peter

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