Originally Posted by weaver122876
Because the engine manufacturer recommends it. They built the engine not the oil company and know what's good and what isn't for the engines they make.. Just my opinion...
In all honesty, I think that has to be taken with a grain of salt. I have generally adhered to a rigid schedule regarding oil changes since I first started operating my own vehicle at age 16, which was more years ago than I care to admit.
For my first 8 or so years of operating commercial mowers, I changed oil and filter religiously at 50 hours, largely because that is what my dealer recommended. Now, partially because of information posted on this site, but mostly because I got tired of changing oil all the time, I have gone to intervals of 100 hours, and am confident that neither myself or the next owner of my mowers, since I tend to trade fairly frequently, will ever notice the difference. I am certain there is a limit as to how far service intervals should be stretched, and oil analysis is certainly one way to find out how long that is.
I suspect the manufacture of any engine tends to err well on the low side in their recommendations, largely to protect themself. They also probably factor in human nature. If you recommend an oil change at 100 hours, there will be those that don't get around to doing so until 150 or 200, in all likelihood doing little or no harm. If, however, you recommended service out to the limits of the life of the oil, which is, let's just say for the sake of argument is around 200 hours, then those same people would goof around until 300 hours, perhaps causing premature wear on the engine, thereby increasing warranty claims, and trash talking about their product on forums like this one.