How much transmission fluid does a 2026 Honda Civic Si take?

2.3 quarts as a total fill for the SDEM transmission (2 to 6.4 quarts across this year's engines). A drain-and-refill without removing the pan replaces roughly a third to half of that, so refill to the level check point rather than pouring in the whole figure.

What transmission fluid does a 2026 Honda Civic Si use?

The source lists only a catalog code for this year, not the OEM specification, so use the fluid named in your owner's manual or on the dipstick.

What brake fluid does a 2026 Honda Civic Si take?

DOT 3, per the manufacturer note. It is also printed on the brake fluid reservoir cap.

2026 Honda Civic Si transmission fluid capacity and fluid specs

GarageDex's fluid data shows the 2026 Honda Civic Si (K20C1 2L 4-cylinder FE-FL) uses the SDEM manual transmission, which holds 2.3 quarts of fluid as a total fill. Other engines on this year hold 2 to 6.4 quarts - see the table. Brake fluid is DOT 3.

Shop transmission fluid Match the specification on the bottle to your manual

Key takeaways

Transmission: SDEM manual transmission, 2.3 qt total fill.
Total fill is the whole system; a drain-and-refill takes a third to half.
Brake fluid: DOT 3.
Fluid specification is not named by the source - use the owner's manual.

2026 Honda Civic Si fluids by engine
Engine	Transmission	Total fill	Fluid spec	Brake fluid	Gear oil
K20C1 2L 4-cylinder FE-FL	SDEM manual	2.3 qt	per owner's manual	DOT 3	-
K20C9 2L 4-cylinder FE-FL	JJ4C automatic	6.4 qt	per owner's manual	DOT 3	-
L15CA 1.5L 4-cylinder FE-FL	E5PM manual	2 qt	per owner's manual	DOT 3	-
LFC3 2L 4-cylinder FE-FL	-	-	per owner's manual	DOT 3	-

Fluids for the 2026 Honda Civic Si

Buy fluid that states the specification your manual names. Multi-vehicle fluids list the specs they meet on the back label - if yours is not listed, it is the wrong bottle.

Transmission fluidYou need about 3 quarts for a full fillShop fluid DOT 3 brake fluidA quart covers a full flushShop brake fluid Fluid transfer pumpMost modern transmissions have no dipstick tube - you fill from belowShop pumps

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Other 2026 Honda Civic Si specs

All specs Maintenance schedule

Other Civic Si years

2025 2024 2023 2022 2021 2020 2018 2017

Source: World's Best Oil (AMSOIL dealer cross-reference). Capacities are total system fills; a drain-and-refill takes less. Where no fluid specification is shown, the source lists only a catalog code, so use the specification printed in your owner's manual - the wrong transmission fluid damages a transmission.