B&S 190cc 6.75 HP motor on a Tr0ybuilt mower. Filled with some Peak conventional SAE 30 oil I had.
I know I changed it when I got it from my mom 4 years ago (she had it for 3-4 years and it was never changed) but can't remember if I changed it 2 years ago or not.
Oil was dark but did not look too bad (but who knows without a used oil analysis). Used about 3 hrs a month June/July/August/Sept, and maybe 1.5 hrs the rest of the year. I probably should change it yearly, but I just don't think about it. I may run this till October then change with some Pennzoil Platinum 10w30 I have (but no vehicles that spec it).
I also sharpened the blade, changed the plug, cleaned the air filter and ordered a new drive belt.