If you really want to go down the oil rabbit hole, check out Bob is the oil guy website. Personally I run 15-40 white bottle rotella and a wix regular filter in my unknown mileage, sounds like a diesel, fluctuating oil pressure vortec.
Amsoil signature in all of my bosses personal vehicles and either Mobil 1 or house brand synthetic in his fleet trucks. With wix filters. Recommend weights.
Mobil 1 or royal purple in my 2012 Tahoe with the synthetic wix filter. Recommend weight.
Redline in all three in my Harley with a wix.
If it gets really hot where you are and/or you’re not very disciplined in changing your oil routinely I would run synthetic. High mileage oils will sometimes soften seals to “help stop leaks” so if you fixed all your leaks I wouldn’t run a “high mileage” oil.