I accidentally added maybe half, or a cup of power steering fluid to my cooling reservoir, mistaking the two. I then drove 400 miles down to chicago and had no problems, no overheating, no check engine lights, nothing.
Because I didn't actually top the right fluid my power steering was still making a winding noise, so I went to a mechanic thinking it was a worse problem. I got there, and he topped off the right reservoir (winding noises went away, problem solved), and I told him I added this small amount of power steering to my cooling reservoir, and he recommend the best thing to do was flush my entire cooling system.
Fair enough, but then he also wanted to replace some thermostat, quoted at $180 for the part, which according to him required the front manifold being removed. My question is, since I had already been driving around like this for hundreds of miles, with no issues, no problems, and such a somewhat small amount of power steering in my cooling reservoir, is it really necessary to replace the thermostat like he says, or would I be fine flushing it myself like I want to (run water through it will a coolant flush additive, then flush that out and refill with coolant)?
Is it common to replace this thermostat? I asked why and if it needed to be done and he was kinda vague and left me feeling unsettled, "oh yeah you know well if you don't replace the thermostat now you might in the future and that'll be another $300?" Is it even necessary to replace this thermostat??
I'm trying to discern between him wanting to do it the totally correct best way versus if it will really make a difference if this thermostat is replaced, and if he just wants business. Quoted me at $600 to flush and replace thermostat.
2012 Jetta 2.5 SE
Thanks for the suggestions.