Castrol GTX High Mileage 5W-30 Synthetic Blend Motor Oil - 6 Gallon Enviro-Pack for Older Vehicles | Engine Protection & Performance Boost | Ideal for High-Mileage Cars, Trucks & SUVs

I am the type of guy who normally uses the top of the line oil like royal purple (40$-50$ for 5 Quarts). I recently started using this oil in my 04 Silverado with 210,000 miles. I've never had any engine issues whatsoever on my L59 5.3. I wanted to try this oil because first off, I was tired of spending well over $60 for 6 quarts of royal purple and a filter and I wanted to see if the "Magnatec" was just a gimmick or a thing these days (most products are with engine products). I have to say the oil definitely keeps the top end of the motor quiet with lifter noise on startup, especially in the winter which is what I wanted. Will continue to use this as the oil seems to hang around in the critical parts when the motor isn't running. With that being said, I have never had to tear down the motor and dont plan on it, so it is difficult to truly tell.Update as of 10/5/18: Getting ready to drain this out of my motor as it is time for an oil change. Dipstick and oil coloration still looks new even at 215,000 miles. This oil still helps on those cold starts where I used to get some lifter noise. Have not heard it since using this.