My 2018 6.2l Silverado just cracked 40k miles. I work at a chevy dealer so for the past 4 years I’ve just had them change the oil with the oem semi synth blend. I’m going to make the switch to amsoil full synthetic so I ordered a case of signature series and figured I try a engine flush. The instructions state that it should idle for 15 minutes after adding the flush right before changing the oil. My question: I live 15 minutes from work- could I simply add the flush on my way to work and get the oil changed? Or should I add the flush and let the truck idle for 15 minutes after I arrive?