Inside your engine looks good tbh. I took the valve cover off my 2az-fe when I bought it two years ago and it looked much worse than your tacoma. I am talking about all metal surfaces stained dark brown like a turd. The previous owner had always used GTX or VWB and changed every 5-7k. The car burns about a quart every 1,500 miles, so I guess that lines up with when the red oil lamp would come on!
T6 is a good product. If you don't like the stains, then try a shorter oil change interval on your next ride.
You got 240k using t6 and your engine looks like that with a 10-15k oci. If you're looking to do it a bit more justice just shorten the oci to a 6-10k and call it a day. If t6 is all its known for 17 years and 240k miles then I'd say t6 is what should stay in it.
The diesel Jetta guys did some testing years ago and found that Mobil 1, 5W-40 Turbo Diesel Truck was the best overall choice in both VW diesel and gas engines. Specifically, the elimination of cam lobe failures in problematic engines. So I switched to it in a number of my vehicles and my OPE. In particular, my Jaguar X-Type with the 2.5 V6. That engine is known for connecting rod bearing wear, especially when using thin oils. I'm at 200,000 miles now and the engine is spotless inside, no signs of bearing failure, excess cam chain wear or other issues.
I agree, looks good for 240k. Curious why you are running T6. Don't get me wrong, T6 is a good oil and has served you well. But IIRC it is not the spec this engine calls for. I would run M1 5w30, 10w30 or 0w40... it's cheap, it's very good, and it's everywhere.