I always tought the computer was set around 7k.
No its not based on mileage or sampling of the oil. Its a computer algorithm that takes in account engine starts, rpms, engine temps and other factors determined by years of testing, in other words driving habits. The more stop and go driving you do, the sooner the OLM will trigger, drive all highway miles and you could go a year and more than 10,000 miles before that happens. OLM are only calibrated for synthetic oil in car that come factory filled with synthetic oil like all Cadillacs since 2005, all Corvette's since the early 1990 and starting in 2011 models you will be required to use a synthetic.
How much oil is lost changing just the filter, a qt or less.
People really think that If it says full or fully synthetic on the bottle that they actually really get a real synthetic oil in this country . All the oil company synthetic's are derived from petroleum base stocks. There are only about 3 main companies making a true synthetic. That is an oil engineered molecule by molecule rather than refined by a special process call hydro-cracking.
Why do they call them synthetics then?
In 1999 - Mobil filed a complaint with the National Advertising Division of the Better Business Bureau in the US claiming that Castrol was engaging in false advertising by calling Syntec "full synthetic" since it was now being made with Group III base oil. (Google it you will find its from petroleum.) Castrol was able to present enough "evidence" to convince the *** that Group III base oil could legitimately be called synthetic, so they rulled in Castrol's favor. This ruling has no "legal" standing. It merely means that as far as the *** is concerned, an oil company is not falsely advertising an oil as "full synthetic" if that oil is made from Group III petroleum base oil. So in other words, the oil companies are using the term synthetic to sell you high priced petroleum oils. They might be better than oils that preceded them buy still are a long way from the true Gr. IV synthetics, some which have been on the market since 1972 (AMSOIL).