Just to point out that you can use the best oil and the best filter and still destroy your engine...it doesn't make it immune to abuse. Constantly trying to jam your mower through tall lush growth traveling too fast and failure to keep the engine free of external debris will likely do more damage than letting your oil change interval slip a bit or using cheap oil and filters.
If you read the fine print in all of these "Tests" and recommended oil change intervals, some where and usually only once will be the word "continious" running.
Also usually there will be both a running hours and a lapsed time, whichever comes first.
Intermittant use items like lawn mowers really should have the oil replaced each & every season, at the end of the season and by prefference just after the final mow of the season, the instant it comes off the lawn.
Weather you change the filter with every oil change is another moot point.
While it might not be "full" to its capacity of particulates, it will still have a quantity of spent oil in it which will contaminate the fresh oil you put in.
Since replacing the oil & filter on most mower engines run sub $ 20 it is sort of a no brainer.
Not that racing is directly compariabe to mowing, most racers I know replace their oil each meet and the really competative ones after each race.
Oil companies & filter companies are always trying to convince customers that their new flash high tech product is substantially better than their previous flash high tech product and the usual way is by claiming that it will run for longer in their engines thus cost you less which charging you more .
