I have a Grohe Euromix Model 33.024,.031,.514,.816 fixture in two bath sinks and 2 shower valves. This valve gets difficult to operate after no more than 7-8 months, whereupon I pull the valve, overhaul it i.e., take it apart, soak it in a water-vinegar solution, lube it, put it back together and re- install it. That works for 7-8 months and then it begins to freeze up in the vertical movement particularly and I go through the process all over. I should say that the biggest problem valve is in the one bath sink that gets the highest usage so there is a relationship between the amount of use and the problem, yet there is only my wife and myself who use it. Also, I have used new valves and rebuilt valves with parts from Grohe. I do not believe we have a high water mineral content in Seal Beach, CA. So my question is, Is my experience abnormal/unusual? I have never experienced this kind of problem with other valves. Perhaps someone can recommend a lube for the rebuilding process that might be longer lasting? What if anything can you recommend for extending the service on these valves?

You have hard water. The average PPM is 136. Other areas in the Long Beach Water District are at 244 average.
Scroll down this link for the 2013 water quality chart.
[www.lbwater.org]