Decided to go ahead and replace the fuel filter today. It still had "38% remaining" but I've already had two oil changes (about 12,500 miles) and I did have an incident last winter that I believe is attributable to fuel gelatinization. A couple of observations:
1) My (old) fuel filter had an actual tear in the filament; see below.
2) There appears to be a drain plug in the fuel filter housing which is only supposed to be tightened to 2.5 N*m, which is less than 2 lb*ft of torque. This is an incredibly tiny amount of torque and unless you have a 1/4" torque wrench you probably will not be able to tighten it correctly. The threads holding this drain plug in are tiny
and appear to be very easy to strip. It's probably easier to just remove the entire filter housing with a drip pan under the thing, slowly lower it down, and pour the contents out into the drip pan than to screw around with the stupid drain plug. Who knows what GM charges for a replacement filter housing and drain plug if you strip the threads (I guarantee it's three figures). See below; let me know your thoughts.
Edit: Okay, this appears to be a drain for removing water from the fuel. In any case, make sure you have a tiny 1/4" drive torque wrench (torque measured in in*lbs) for draining water. A 3/8" drive wrench will probably not have small enough adjustments to keep you from stripping these threads. I discourage anyone from tightening it "just enough" (without a torque wrench) because you'll almost certainly over-tighten it and hop/strip the threads.
Edit: If you do strip it, it's not the end of the world: https://www.ebay.com/itm/New-GM-Fuel...-/202163738516
3) After I put everything back together, I fired 'er up to check for leaks. I was worried because when I was screwing around with the drain plug I over-tightened it and the threads "hopped," and my heart skipped a beat because I thought I'd stripped them. Fortunately it seems to be working fine; I let it idle for about twenty minutes with a drip pan underneath and didn't see any issues. However, I noticed for the first time a noise that seems to be coming from the fuel tank area; it sounds like a pump trying to suck liquid out of something but with the intake only partially submerged (my fuel tank is 3/4 full in the video below). It is a little hard to hear because of the sound of the engine, but in the background you should be able to make out the sound I'm describing. Does anyone know what that is?
4) I was unable to get a picture of this due to the angles involved, but there appears to be some kind of heat exchanger connected to the fuel system. It's near the fuel filter. Can anyone explain what that thing is, and what it does?