So my 2002 5.3L has gone through about a quart of oil since the last oil change. The check engine oil level light came on today and the dipstick was pretty dry. Pretty sure my sending unit is bad considering my oil pressure needle shakes like crazy at idle. Anyone have possible causes of oil loss? No leaks on the garage floor but getting some drip marks coming down towards the oil filter possibly from the back of the engine. I'm wondering if my sending unit is actually starting to leak once the engine is running, so I could be leaving my oil on the road and not on my garage floor where I can see it. Any advice? Common spots for oil loss? She's been well maintained since brand new. I switched to synthetic oil a couple oil changes ago, maybe it's too thin for a truck with 150k on it. Definitely switching back to regular motor oil to prevent fast oil loss. I don't think she's burning it. No dark smoke out of the tailpipes. If anything it might have a slight white smoke coming from the pipes.