2000 Toyota Celica GTS - Oil questions, help, opinions, and experience sought.

I love this thread since I own a 2000 GT-S 6 Speed. I purchased it brand new in September of 2000 and now twenty-one years later it has 29,000 miles. The Celica is my summer fun toy. I don't use it much, but I still love it!
I only put about 500 or so miles on it per year now so I only change the oil once per year. I use the OEM Toyota oil filter and Mobil 1 5w30. I have thought about trying a different oil but I usually say to myself, the Mobil 1 5w30 has worked great for the last 21 years, so I guess I should stick with it.