Ditto on that Mrbb. How often have you been changing your oil? It looks like one manual I saw online suggested every 100 miles or 6 months.

I base my oil changes on HOW hard I work the motor and where the motor is being run at(as in say a very dusty area or super hot out or??)

say I am dragging a disc or a harrow about for 15-30 hours in a week and do that a few times, I might do an oil change in 50 hrs or less, as that is a LOT of very HARD use/abuse on a motor running in low gear with NON stop resistance on things
way harder than say traveling down trails and up and down smaller hills
I have been known to change oil maybe 6+ times a yr
a normal yr for my atv and oil changes is 4 a yr min
I change it before winter, say as I plow a lot of snow with it, which I also see WORKING the motor very hard I plow MILES of trails at a time, some 4-+ mile loops and drive ways over a 1/2 mile I open up 20+ ft wide
so, a oil change before winter(someines in a LOT of snow yrs, IN WINTER time too) and thehn in spring time before doing any food plot work or just due to using all winter hard!
the amount of use it gets in spring time, but in yrs I do a LOT of remote plots, it might get changed 2-3 times
some MIGHT think this is over kill, but its 20 yrs old and motor runs like new, average speed per amount of hours on motor is like 1 mph or less
its been a work tool for me, and NOT a toy, used around the farms and on rural homes
its towed trailers over 3,000 lbs for HOURS at a time
SPraying is a SLOW going HOT weather deal, and it can make a ATV motor HOT< burn your legs hot
so, to me, OIL is way cheaper than down time and larger repair parts
my one tractor is a 1949 model and it also runs like new yet, change oil in that more often than others too since I got it
I DON"T baby my machine I WORK them and some time's for sure OVER work them, I rather new oil in than than ??
this is what I DO< I do not expent anyone to do this due to how I do,
but its been working for me, never had a motor fail on me yet and I have owned a LOT of things with motors now!

I also change gear oil and trans oil more often too, and I also clean air filters WAY more often than most
long life of anything IMO is HOW you treat and care for it, more than some times the MAKE?BRAND of it!
I ain't made of money, so I like my things to last as long as they can LOL

Update. I finally got a chance to use the new honda quad yesterday since I bought it. I worked it hard all day and I like it.

I limed, fertilized. and sprayed some post plus on 3 of my clover plots.

I roundup two other plots, plus seeded buckwheat, lime and fertilizer in another 1/2 acre plot. Then I hooked up my cultipacker and dove over the plot. .