Put an inline temp guage right before your hydroforce, it will remove all doubts about where you are really at laying down the chems. 2 bills ATM will be under 175° on a live reel that's been smoking it for a while. On a cold start don't sweat it, the hydroforce will pull chems at almost 100% until about 190°, then it boils at the cone of the venturi and it cavitates and pulls less chems. If you have a high heat machine increase the gun jet size a tick and reduce back pressure for better injection. Other tricks work as well.
It takes years of high temp use to wear out a block, the bottom of the brass nozzle inside the block wears first and needs replacement much sooner. If you use a SS nozzle you will get 3x the mileage easy. YMMV, but that's what I have seen for the most part over the years.