Sitting for months in the collection container? I drained the oil on our 13 Altima today. I noticed that the residue sitting in the bottom of the collection pan was sludged up from the last oil change. The collection pan has been sitting in my garage. I've noticed the same in my mityvac that I use in my jeep and boat. I'm hoping this is happening in the collection containers, not my engines. All engines get changed on regular schedules.