How much oil does a K20 transmission take?
Typically about 2 quarts (approximately 1.9 liters) of gear oil are required for a drain-and-fill on a K20‑era manual transmission. The exact quantity varies by model and whether you’re working with a 5‑speed or 6‑speed unit, so it’s best to consult the specific service data for your car.
Understanding the K20 transmission family
The K20 refers to Honda’s K‑series engines, which were paired with several manual transmissions across different model years. While the basic principle is the same, fill quantity can differ slightly between 5‑speed and 6‑speed units and across revisions like K20A2, K20Z1, and others. Knowing your exact transmission code helps pinpoint the precise capacity.
Oil capacity by transmission type
Below are typical drain-and-fill capacities for common K20 transmissions. Exact figures can vary by year and model, so verify with the factory service data for your car.
- 6‑speed manual transmissions (common on many K20Z and related variants) — about 2.0 quarts (1.9 L).
- 5‑speed manual transmissions (older K20 configurations) — roughly 1.8–2.0 quarts (1.7–1.9 L).
In practice, plan for around 2 quarts, with a small allowable range depending on the specific unit and whether you’re draining completely or performing a simple drain-and-fill.
Fluid recommendations and filling procedure
Choosing the right fluid and following the correct fill procedure are essential for longevity and smooth shifting in a K20 transmission.
- Use Honda Genuine Manual Transmission Fluid (MTF) or an equivalent GL‑4 rated 75W‑90 gear oil. Most K20 transmissions are filled to a level at the fill hole; avoid using GL‑5 fluids which can harm synchronizers.
- Typical capacity for drain-and-fill is about 2.0 quarts. Fill through the designated fill port until fluid starts to seep out of the fill hole, then reinstall the plug and wipe away any overflow.
Following the manufacturer’s specification for the exact fluid type and fill level helps ensure proper operation and longevity of the transmission gears and synchronizers.
Variant notes
K20A2 / RSX Type S (DC5) and related 6‑speed configurations
These 6‑speed units generally align with the ~2.0 quart drain-and-fill capacity. Use the recommended MTF and verify the level through the fill plug area after a complete drain and refill.
K20Z1 / Civic Si (FG/FD variants) and other 6‑speed implementations
Similar capacity expectations apply, with minor year-to-year variations. Always confirm with the specific service data for your exact model and year.
Summary
For most K20 manual transmissions, plan on approximately 2 quarts of gear oil for a drain-and-fill service, with a typical range of 1.8–2.0 quarts depending on the exact transmission model. Use a GL‑4 75W‑90 or Honda MTF, and fill to the proper level as indicated by the fill plug. Always verify the exact capacity for your year and transmission code in the official service manual to avoid under- or over-filling.
