Your mechanic and grandpa are both barking at you to get your oil changed every 3,000 miles. But cars have advanced past the Model T, and what we use to lubricate our engines is a bit higher-tech than ground-up dinosaurs. Many of the “I change oil in the spring and fall” diehards are throwing good money after bad. But how far can you push your oil? You should probably trust your owner’s manual and definitely trust your dashboard warning lights. Read on to see why some new cars recommend 20,000-mile oil change intervals.

How long can you go past due for an oil change?

Don’t go “past due” unless your manual recommends long intervals. If your dashboard oil light comes on, change it now—your car knows better than you.

If your mechanic suggests 6-month changes, but you’re barely driving, you might be able to stretch it to a year. But this depends on your specific car’s maintenance schedule.

AAA says modern engines running synthetic-blend or full-synthetic oils often can go 5,000 to 7,500 miles before needing a change. Some can even go 15,000 miles (AAA). But if you’re still rocking conventional oil, don’t push it too far.

Can you go 2 years without changing oil?

Only if your car’s manual explicitly says so—and even then, think twice. If you can’t get the recommended high-mileage oil type, work your engine especially hard, or hit the mileage limit–just get a change.

As I previously wrote, European automakers engineer cars for longer intervals. The Mercedes E-Class sold in Europere recommends 20,000 miles or two years between changes. Why? Bigger oil sumps, long-life additives in all oil, and synthetic-only requirements.

But if you’re in the U.S., your oil doesn’t last as long. American standards allow lower-quality oils, which break down over time—even if you’re not driving. That’s why AAA says most manufacturers still recommend changing oil once per year, minimum (AAA).

Can I really go 10,000 miles between oil changes?

If your manual and dashboard oil monitor say yes—you might be in the green. But again, if you hit your time limit (usually a year), are hard on your engine, or can’t get the correct high-mileage oil–then change it sooner.

As I previously wrote, oil tech has changed. Old-school 3,000-mile changes were a relic of cheap, low-detergent oil. But modern synthetic oils? Way better.

Firestone Complete Auto Care even says you shouldn’t change oil before 3,000 miles unless your car specifically calls for it. If you’re running synthetic, 10,000 miles may be recommended. But if your older car calls for 6,000-mile changes, why are you even asking? Change your darn oil!

The bottom line: Trust your car, not your grandpa

Oil changes aren’t one-size-fits-all anymore. Trust your manual. Trust your dashboard light. And if your car lets you push oil changes to 10,000 miles or more, enjoy the savings—but don’t cheap out when it’s actually time to swap.