Hi Scotty. I have a 2004 GMC Yukon XL with 220,000 miles, 5.3 L. Whenever I add oil or do oil changes, the dipstick doesn't read unless the engine is either running or has just been turned off. It's hasn't had regular oil changes, so could this just be sludge buildup in the dipstick tube? If so can I use some Seafoam to try and clean it out? If not what else can I use? Won't let me upload photos, so I'll including a Google Drive link to them, says file size is too large when I try to upload. Thanks!
https://drive.google.com/drive/folders/1eiP6svOEHLTs3xMf8Wqkjhp9PBct8SpC?usp=sharing
That does look like a tremendous amount of sludge. Does the engine burn oil in between changes?
If yes, I would start by getting a small diameter brush on a long handle (like one used to clean gun barrels) and clean the tube out.
If it doesn't burn any oil between changes, I don't know if I'd use Seafoam, but in either case I would definitely make sure I was using quality high-detergent oil and changing it and the filter frequently (you must be doing something right, most cars with 220K on them are in junkyards)
It does burn oil between oil changes. It's getting past the piston rings, and leaks a little bit. It's mainly burning it, though on startup it smokes for a few seconds, then stops. Problem is I can't tell exactly how much it burns due to the dipstick not reading, so I have to guess on how much to put in. Truck survived having 24 quarts of oil and misfire from a plug wire in the wrong spot, including going exactly an entire year without an oil change. It's proven more than once it's not dying without a fight. I will definitely get the brush like you said and try that.
(I did clean the valve covers and change the gaskets after taking those photos, as disgusting as they were it runs tremendously better now.)