Power steering fluid - when to change? (2013 Mazda5 GT)

I got an oil change today at 42k and the tech suggested changing the power steering fluid. He showed me a drop of the fluid, which looked a little off color but not terrible. I did not agree to the fluid change because it seems too soon and because he wanted $120 for the job, which seems a bit much. My service manual doesn't say anything about the interval to replace the power steering fluid; "Schedule 2" just says to inspect it every 5k miles. Any thoughts on a service interval for the power steering fluid? (I am a pretty normal driver; 1/2 highway and 1/2 city down here in very flat/hot Houston.) Thanks.

I'm at 50k and about to change it, just need time.
I'd day it is cheap insurance to change. You can do yourself, I should have how-to next few month.
It is not super hard to DIY.

Same guy that was telling you to change your ATF fluid after you just had it changed. Again, don't listen to quick change guys, they're just pushing for a sale on a service. Generally Power Steering fluid is something that isn't really ever recommended for a change. I don't believe PS fluid actually lubricates anything does it? Think it's purely a hydraulic fluid so it's not seeing much wear and tear other than pressure.

Geeze these guys were really trying to get to go for the whole meal deal weren't they!

True that some places out to get you. I changed a fuel filter on a friends car, a week later he went to do oil change at Mr. Lube and they suggested him to change the fuel filter as the current one looked very old
Even though it was nice, new and shiny...

But old power steering fluid ... as everything it goes bad. It does lubricate the pump and internal rack parts. It eventually build up contaminations and should be changed.
I don't see 3-4 years as super upsell...
Id rather change it and know it is done then experiment with life of power steering equipment.
Even at $120 it is what, perhaps once or twice things to do in the average car's life before you get a new toy, not too bad in my books
But perhaps I read different books (drunk)

All fluids serve a purpose (lubricate) and is prone to deteriorate b/c nothing lasts forever (rate of breakdown is subjective to conditions you drive and live in). The only way to know for sure is to send in an oil sample + $25? to an oil analysis firm, like Blackstone Labs. I exchanged fluids at 80K and I’m sure I could have gone longer (it was squealing). My power steering certainly works better and quieter after the change. This is not to say you ‘have’ to do it b/c you are likely to sell/trade the car before noticeable/permanent problems propagate so this is someone else’s problem.

My experience and some tips. The idea/effort is almost EXACTLY like an ATF oil change using the transmission pump. You disconnect a hose and let the pump do that work to flush oil out. The difference is you need to turn the steering wheel to activate the PS pump unlike the transmission pump which runs once the car is started.
http://www.mazdas247.com/forum/showthread.php?123845663-Power-Steering-Oil-Change

Many how-tos on the web and even youtube, IIRC. The golden rule: Mada3 = Mazda5 (how tos)
http://www.flex-innovations.com/power_steering.htm