I run a semi-synthetic 5w30 too (what many shops now consider good "conventional" oil) ....after being in the repair field for over 25 years, the common demoninator for long and strong engine life is frequent and consistent oil changes. I feel it is more important than the weight of the oil as long as a quality multi-viscosity is used.
Ive recently saw a new v6 Toyota engine get ruined by not ever changing the oil for 35K miles. Ive also had engines apart (for valve cover gaskets, oil pan reseals, etc) on engines with over 300K and you could eat off the metal it was so clean and virtually no discernable signs of wear. The owners of these kept themselves to a regimented oil change schedule.
I dont drive my 80 much these days but still change the oil every 6 months regardless of I hit my 4K oil change interval. Even though Toyota says 5K, I do it sooner for good measure which is one extra oil change every 2 years. Cheap insurance in my mind.
Ive seen A to Z on maintenance. Some that make you proud and some that wants to make you cry ~ thankfully Toyota owners are overall one of the most maintenance minded people there are (next to Honda) according to the report people.
Must be why our Cruisers last so long....
