Dealerships relie on 80% of the business from maintenance service from return customers such as oil changes, now do the math you buy into the 3k oil change intervals at a minimum the dealer gets 20 bucks for herding the cars in and out, thats 300 bucks for every 15k on your car compared to 60 bucks if you change the oil every 5k, thats 240 dollars more for throwing away oil

the dealer just made several thousand dollars for the day and paid some kid not even 100 bucks, but cause you feel better good for you
Step up to Lexus or BMW and the oil changes vary from 60 to 100 bucks, yeah it's pure profit.
If the oil companies start to advertise 5k, 7k or even 10k they would loose millions, people bring their cars in like clock work to change the oil.
Toyota advertises 5k and 7.5k on dino oil so whats the problem, if they decided to make a 3L sludge engine that supposedly sludges up with routine oil changes thats their fault, the extreme heat in the head with the oil being sheared is what sludged it up, is 1 of many reasons I have been told but yet I've heard from people who changed the oil frequently and still needed new engines.
Both my 4Runner and ES will get changed ever 5 or 7.5k on dino.
People will change their oil every 3k and neglect every other fluid in the cars, thats brain washing the public, at least the car makers are changing the standard with longer intervals

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