D. McKeithan

I have a 2018 Chevy Silverado 6.2l with the 8L90 transmission, which had the shudder and a hard shift since 50,000 miles or so, I'd change the transmission filter and fluid around 54,000 miles, shudder went away and returned around 58,000 miles. At 72,000 miles I purchased a 12V vacuum pump, vacuumed the two oil cooler lines, drained the transmission and replaced the transmission filter, went back with 7 quarts of the AMSOIL special blend transmission fluid, and immediately the shudder went away and the shift is so much smooter.