When I was a kid in the late '60s my Grandfather would put $1.00 of gas in his Chevy II and drive from Wash. DC to Stafford county and back, 82 miles round trip.
I don’t think he ever filled it over halfway.
My father OTOH never let his tank go below 3/4.
My Dad had a gas station in the late 60’s thru the early 70’s. There was a gas war in town. He got down 10 cents for almost a week.
Lets back it all up.
A quart every 3months (assume 3000 miles or even 1000 miles) is NOTHING to be concerned about an 11yr/225,000 mile car.
Buy the recommended oil and check/top every 3-4 fuel fillups. This is good advice for a brand new car or an oil burner(your car does not really qualify likely).
The car made it 225k on the proper oil, why mess with success thus far???