O2 Sensor replacement interval

E150, 4.2, auto. This is an 01.

When will I need to replace the O2 sensors, an estimate?

What will be the indications that this should be done?

Will there be a performance indication first or a gas mileage notice?

Currently, the sensors are at approximately 130,000.

u only replace them if you have a problem, your engine light will come on and a code for them will be set and as far as when or how long its impossible to say for sure ..

Well, I didn't know that. Learn the most useful stuff here.

So, I will let it tell me; meanwhile, "keep on trucking"!

Thanks,
Doyle