Ok. I’ll bite, haha. The manual will state quicksilver 25w40. Should you want to go with that, I’d recommend you to get the synthetic blend version of the brand.
The reality is though, that many other people use this very engine in identical form, all but the badge, small tweak or sticker on top. These other brands of the gm will often state 15w40 or a few other close grades.
You’ll need at least 5 litres for the 4.3. Unfortunately and rather cunningly, the recommended quicksilver oil will come in a 4 litre or 1 litre tub, usually. Basically take your pick, but that’s the basics of it.
