I work at a gm dealer as an apprentice, so Ive done a lot of oil changes lol, and basically no matter what type of oil you put in, we just write every 5000 km or in your case 3000 miles, I wouldn't worry too much, personally even with synthetic oil I change every 5000 km, people say its a waste but it wont hurt it
Also I do everything myself but make sure you keep all your receipts of the oil you buy when you do it yourself, they can request that and if you have no logs or receipts and a major engine problem occurs they can void your warranty because you have no proof of ever changing your oil.