Between these posted would all agree that they are trusty standard drain interval and clean running idiot-proof OTC dino's. I am a Royal Purple and Mobil 1 user myself but from reading the past months posts here are my conculsions:
Texaco Havoline(s)
Castrol GTX
Mobil Drive Clean
Exxon SuperFlow
Kendall
Any other add-ons? I would add Shell although I have no experiance with thier products.
Thanks-