00 Toyota Tacoma 3.4 - 7500 miles on Royal Purple HMX 5w-30. On it's third time using this oil. Overbuilt, underpowered engine that loves low RPM's. 129,000 miles
04 Corvette LS1 - 4000 miles on Mobil 1 High Mileage 5w-30. On my second use now. I used this oil to stop an oil pan gasket drip the second I saw it, and it worked! It's driven hard. Will be switching to HMX like in the Taco because it's still API SL. 130,000 miles
13 Jeep Grand Cherokee 5.7 - 5000 miles on first use of Royal Purple 5w-20 API SN. My mom's Jeep sees a lot of highway and city. Will crank it to 7500 next. I swear I've never heard that Hemi run so smooth compared to the dealership oil. 42,000 miles.
All 3 use the STP XL oil filter that is rated to last 10k miles. That oil filter uses a silicone ADBV and gasket with a coil spring.
I go 1 year MAX on synthetics if I don't make the miles. All vehicles run long enough to get hot and evaporate water. Living in a desert, I wouldn't dare push any synthetic past 7500.