When is it time to change O2's?
 

When is it time to change your O2 sensors? Will I know when it's time? Silly question, but I've never come across it yet.

I believe 30,000 miles or 30 mths which ever comes first.

BAH! My car 90 has 92K on the ODO and still has the stock O2 sensors! As long as you aren't experiencing problems (gas mileage) don't waste your money.

true
 

When I got my car she wouldn't pass smog. So the O2 sensors were the first things that I changed and at 147,000 miles I'd bet they were the originals.

Will a bad O2 sensor cause any performance problems?:confused:

Yes they will. 02 sensors are in your exhaust pipe and they "sniff" the exhaust gas to see if your engine is running rich or lean. if they aren't working correct your fuel mixture can be off and keep you from passing emissions if they test where you are. also if your fuel mixture isn't correct then engine performance and gas mileage can suffer.

O2 sensors are something that should be changed before you notice that there is something wrong. I'd say every 60000 miles.

O2 Replacement Interval
 

the Ford Repair Manual states 100,000 miles as the interval for 02's...for what it is worth.