Hey y'all, I have a 2001 Chevy S10 with the 4.3 V6 that just hit 200k miles. I love this truck. And it's a manual! My goal is to reach 300k miles without any major repairs, and I'd like advice on engine oil. A bit of background- I do keep on top of maintenance, but I also use it like a truck. I haul around welders and riding mowers, drive on dirt roads, and occasionally I end up towing over 6,000 pounds. What I've been using is Valvoline Maxlife 10W30 semi-synthetic with a WIX filter, changed every 5,000-6,000 miles. I don't know if I should stick with this or try something fancier. What are good options? I'm just trying to do the best for my engine, so all input is appreciated. Some of the options I considered- Sticking with 10W30 Maxlife Pennzoil Ultra Platinum 10W30 Schaeffers SynShield 10W30 or 15W40 diesel oil Rotella T5 10W30 or 15W40 diesel oil Is thicker oil a bad idea? Is diesel oil a good thing in a 4.3? Should I be leery of stretching my OCI? As a side note, I do have a few small leaks and a tiny bit a of blow-by, which the Maxlife helps with. If I go with a non high-mileage oil and it starts to leak more I'll add some STP stop-leak to it, which has worked great for me in the past.