Had an appointment for a oil change on a ZR2 Colorado. Everything went good until I drove off, then the vehicle smoked, when took off from the light, the smoke was the size of a house. Pulled over, oil leaking all out of the air cleaner. Turned out they didn’t drain the old oil out and just filled up with 6 litres of new oil. Filled everything full of oil, air cleaner and in takes. Luckily I didn’t go far or could have blown seals out.They did tow vehicle back and where apologetic, but took about 5 hrs of my time to sort out.Not very professional and won’t go back.