I will never-ever understand this 3-5k OCI. Every(sorry no data) so most of the modern engine oils will last at least 10k km (6.25k mi)
or longer, even in winter with 10 cold starts(quite impossible) per day. Do You think I could not afford it? Why are You wasting the stockpile of the Earth so light-minded? (And I'm not a Greenpeace guy) Why don't You collect Your 3k oils and send it to me? I would use them for another 15k, sleep very well and throw my cars with half milion kms to the graveyard without a doubt.
And yes, I'm trying to be the smartarse in this.