I recently purchased a 2017 Silverado LT Z71. After a couple of weeks I took it to a touchless car wash. Since doing that my oil pressure drops from dead center to the low quarter mark. My voltage drops from dead center to just above 9. My dealer informed me that these are normal...can anyone confirm? If it were"normal", went did it only start a couple of weeks after having it and nit immediately? It fluctuates on both gauges from perfect to low and back periodically while driving and parked. Any help is appreciated. Thank you

 

Does not sound normal to me. My 2013 doesn't do it. I would find another dealer.