Engine oil and filter

Summary

Source: owner's manual / last verified 2026-10-16 (2021 Hyundai Sonata owner's manual, recommended lubricants and maintenance (opens in a new tab)).

Safety

• A lower grade than API SN PLUS full synthetic changes the interval to the severe line.
• Do not invent a drain-plug torque.

Symptoms

• Normal schedule: replace the engine oil and filter at every column. Columns are 12 months and 8,000 miles (13,000 km).
• If a lower grade than API SN PLUS is used, change the oil and filter every 5,000 miles (8,000 km) or 6 months.
• Severe usage, conditions A through L: every 5,000 miles or 6 months. After 10 years or 100,000 miles, the book recommends the severe schedule.

Diagnosis

1. Smartstream G1.6 T-GDi: 5.07 US qt (4.8 L), drain and refill. Smartstream G2.5 GDi: 5.49 US qt (5.2 L), drain and refill.
2. SAE 0W-20, API SN PLUS/SP or ILSAC GF-6. The footnote requires API SN PLUS or above full synthetic. Mineral oil, including semi-synthetic, is the lower grade that moves you to the severe oil line.
3. The viscosity chart prints 0W-20. Temperature bands stay on that chart.
4. No drain-plug torque is printed. Clean around the plug before you open it.

Tools

• Drain pan

  For the used oil. No drain-plug torque is printed.

• Funnel

  For the refill. The two engines are not the same quart.

• Clean rag

  Clean around the drain plug and the dipstick before opening them.

Specifications

Steps

1. 01Match the engine

   G1.6 T-GDi is 5.07 US qt. G2.5 GDi is 5.49 US qt.

2. 02Use 0W-20 API SN PLUS or above full synthetic

   The table also accepts API SN PLUS/SP or ILSAC GF-6. Mineral and semi-synthetic oil is the lower grade in the footnote.

3. 03Change on this schedule

   Normal: every 8,000 miles (13,000 km) or 12 months. Lower grade or severe: every 5,000 miles (8,000 km) or 6 months. After 10 years or 100,000 miles, use the severe schedule.

4. 04Do not invent a drain torque

   None is printed.

Common mistakes

• Pouring 5.07 qt into the 2.5.
• Stretching a conventional oil to the 8,000-mile line.

Parts and tools

Outbound links only. BaySheet does not sell parts. Confirm fitment on the retailer page. Amazon links are searches for a real part name plus this vehicle. Tool rows do not get a product search. The search is not a part number.

• Part

  SAE 0W-20 API SN PLUS full synthetic

  Required grade for the 2021 Sonata. ILSAC GF-6 or API SN PLUS/SP is the classification line.

  2021 Sonata recommended lubricants (opens in a new tab)Search Amazon.com (affiliate link) (opens in a new tab)As an Amazon Associate I earn from qualifying purchases.

• Tool

  Drain pan

  For the used oil. No drain-plug torque is printed.

  McMaster-Carr drain pans (opens in a new tab)

• Tool

  Funnel

  For the refill. The two engines are not the same quart.

  McMaster-Carr funnels (opens in a new tab)

• Tool

  Clean rag

  Clean around the drain plug and the dipstick before opening them.

  McMaster-Carr shop towels (opens in a new tab)

Questions

Sources

• 2021 Hyundai Sonata owner's manual, recommended lubricants and maintenance (opens in a new tab). Hyundai Motor America. Published 2020-08-20. Read 2026-10-16.

Checklist and email notes

The maintenance checklist is on the site now. The email list is not sending yet, so this box will not store an address.

Other repairs on this 2021 Sonata

All Hyundai Sonata repairs

This repair on other vehicles

These guides cover the same kind of work. Their numbers belong to those vehicles, not to this one.