“Interested in hearing from those with technical knowledge about the differences between the oil environment in cars versus motorcycles with wet clutches, and those who have actually gone longer than the recommended interval on purpose”.
Not many posts lately have dealt directly with that topic. I move to close the thread unless the OP is still getting value out of it.
I do the 8000 miles as that is what I rode roughly in 1 year. But since having a kid, that's down to 2500 miles a year. So now I go 2 years and come out to about 5000 miles on the oil and filter. I have a 2012 nc700x DCT which actually has 2 oil filters. I have a 2016 honda accord that has 130,000 miles and counting. I change that when the OLM pops off at 0% left. Thanks to honda I can use the car oil filter on the honda motorcycle and only stock model of filter for my rides. I have no qualms about going long oil changes with proper synthetic oil that meets the required specs of said vehicle. I have nearly 27,000 miles on my NC700x. I change the little DCT filter at 15k intervals, makes the major service intervals easy to remember, Every 15k, adjust valves, check plugs, drain the radiator (never a full coolant drain), check chain aliengment, Change air filter, change brake fluid, change fork fluid. You know, the big overhaul. Usually takes me 2 weeks to do it all but its winter and I have 5 months to complete the task in the garage.
My wife rides a 2014 Honda CBR250R which gets an oil change when I change my motorcycle. She does not ride that much and maybe 1000 miles a year. I just do it when I change mine for easy to remember oil change intervals, and well 2 years of oil sitting in the sump. Factory recommended is 8000 miles.
I just purchased a 2020 Hyundia Palisade which will, follow the following, 1000 mile change, 3750 (dealer free oil change), then 7500 mile (manual max limit for synthetic oil) for the rest of its life.
I believe the biggest factor now is a proper long duration oil filter. Combustion products carbon and water, the oil filter filters the carbon out, and heat evaporates the water. I try not to ride short intervals often.