Maybe not all 4, but definitely replace them on pairs, like both front sides or both back sides. If you replace just 1 set on 1 side, then the pads on that wheel will always need to be changed at a different time than the rest. You want them to wear at an even rate so you aren't constantly replacing 1 set of pads at a time.

Imagine if you replaced 1 set of pads every time 1 set got worn. Eventually you would be changing all 4 sets at different times, drastically increasing the labour over the life of the vehicle. Besides, brake pads are typically sold in pairs for each side, front or rear, anyway. Just replace the pads opposite the ones that are worn as well and you will be fine.

It sounds like something caused that side to stick. Probably just dirty, stuck caliper guide pins. Have them clean the pins with a wire brush and you should be fine. Worst case the piston in the caliper is stuck, which means you would need a new caliper.

You should only have to change two...either the front or back, wherever the 1mm one is. I don't know why they'd tell you to change all four? I just took my Nissan in for service (also at dealership), and mine were 4mm and 3mm....they recommended that the 3mm ones (back) be changed soon (I think at 2mm they recommend changing). They didn't say I should worry about all four.

Consider new pads. Ask to see a set. You will see that they are thick mothers Like 10mm or more. Zero mm is too little and you start to gouge up the rotor. Now the cost of brake repair jumps 5 fold.

- You are at that stage they got to be swapped and I would do the front set of wheels and do both sides(driver and passenger) The rears may last till the next time you need fronts(then you do all 4 wheels) It is hard to say because it depends on your driving style. Keep an eye and ear on the back ones in case they wear out sooner(ask, they will show you what to watch out for or what to listen for.) Brakes usually squeal before they are gone...which means you do them now.

You are on the hoist now, so have them do the front.(as I assume the front is where they found the 1 mm pad. Do both because that is how they are sold and done.

Sounds like one of the pistons in the calipers is not releasing when the brake pedal in released,

You could replace the pair on the same axle but the 4mm is not a lot left when you consider new ones have 10 - 12mm on them and it only has to go to the shop once instead of twice.

I guess it depends on your money situation

Don't know what an oil change has got to do with it

The dealer said all 4 need replacing. They didn't have a reason why one brake pad was so low. There was no debris. It's a 2003 Nissan Maxima. It was fine at the last oil change.