I'd hate to go against the grain on this one...but, oh what the heck!
My 88 e30. Never had a dose of this stuff, yet the internals of the head were as clean at 18 years of age and 150k miles as an engine that's just been built. The first owner ran GTX for the first part of the cars life, then the 2nd owner ran only M1 until 03 whe I acquired the car.
Needless to say, I was very shocked to pull off the valve cover and find things SO CLEAN! Mind you, the PO used the car for a fair amount of highway driving, and used only dealer or Wix filters with the M1. I'm not sure of his OCI's, but it was probably no more than 8,000 kms per change.
this just something to consider as I personally don't feel the need to use something so strong that strips gunk off at an alarming rate as AutoRx.
To each his own I suppose
happy motoring!