al right guys. this oil change is a scam too. they make a lot of money over oil change so keep in mind:
if an oil says its for 5000, do not change before 5000 or 10000 or whatever the range is. if you are too concerned, check the viscosity physically. you can also learn from checking oil if once its being changed. an 8000 km oil is a just a slightly different then a 5000 run oil.
also, the ranges on oil boxes themselves have a cushion of 500-1000 km. so in reality, you must use a 5000 km oil upto 6000 or 6500 specially in a intra city run.
You can also tell by the drive of your engine when it really needs an oil change. also, do not mix the kick you get out after oil change with air filter. air filter also tremendously improves engine performance initially.
all i want to say is that be easy on oil change. you must always go over limit the ranges mentioned; just dont change if before the registered limit specially if you are not flooring the car.
I have driven 2 honda civic & a city with 6500 oil change regime against recommended 5000. mileages were 165000. 50,000 & 80,000. smooth as silk. even when i drove till 8000 once, the ustad je couldnt guess if the oil has viscosity issue. so just relax guys.
https://carfromjapan.com/article/car-maintenance/how-long-does-synthetic-oil-last/
https://ro.championlubes.com/en-us/news/mythbusters-5-essential-facts-about-motor-oil
https://www.oxmoortoyota.com/service-center-home/service-tips/how-often-to-change-synthetic-oil/
I am open to valuable feedback from experts because i beleive this oil change is among the industry bluffs as well.
"This is a common tactic used by personnel in automotive repair and quick lube shops. Most of the synthetic oils today can go from 6,000 (10,000 km ) to 10,000 miles (16,000). Higher-quality oils can last up to 15, 000 miles."