I'm funny about oil changes. I've only had someone do it a few times. I can count on my hand. In my I had an oil cap not put on once. Asked the guy (service Manager) for a rag to check the oil level he walked out with me, popped the lid, and there it was sitting. Mind you, the guy that changed the oil drove it out. I was in the waiting area.
When we were walking out to the car I chatted how I did own changes and I always double checked.
Boy was he surprised when the cap was on top of the engine. He was good about it and offered me my next change free.
Nope.... Never went back. Do my own changes.. Thank you.

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92 300D 2.5L OM602 OBK #59