KEI Truck Maintenance & Fluid Cheat Sheet 

Japanese KEI trucks are reliable when maintained properly, but many owners in the U.S. don’t have manuals in English. This page is a high‑level reference for common service items. Always confirm specs for your exact engine and model and follow torque specs and safety procedures.

⚠️ Safety note: If you’re unsure about any procedure, work with a qualified mechanic. Many KEI parts cross‑reference with U.S. vehicles, but always verify before installing.

Common Maintenance Items

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Spark Plugs

• Interval: often every 20,000–30,000 miles or as recommended in the manual.

• Type:

  • Many KEI trucks use standard copper plugs from NGK or Denso.

  • Some owners upgrade to iridium for longer life and smoother idle.

• Tips:

  • Replace all plugs at the same time.

  • Check for oil in plug wells – can indicate bad valve cover gaskets.

  • Always start threads by hand to avoid cross‑threading the aluminum head.

Engine Oil & Filter

• Change interval: commonly 3,000–5,000 miles or annually, especially for short‑trip use.

• Typical viscosity:

  • Many owners in New England use 5W‑30 or 10W‑30 depending on the engine and climate.

  • Check your engine spec; some older engines call for 10W‑40.

• Tips:

  • Warm the engine before draining for more complete oil removal.

  • Use a quality filter from a trusted brand; some KEI filters cross‑reference with small U.S. car filters.

  • Check for leaks around the drain plug and filter after the change.

Transmission Fluid (Manual)

• Interval: often 30,000–60,000 miles, or if you’ve just imported a truck with unknown history.

• Types:

  • Many KEI trucks use GL‑4 gear oil in the transmission; some require specific viscosity (e.g., 75W‑90).

  • Do not substitute GL‑5 in transmissions that explicitly require GL‑4 (can be harsh on yellow metals/synchros).

• Tips:

  • Always remove the fill plug first to make sure you can refill before draining.

  • Fill until fluid is just at the bottom of the fill hole unless otherwise specified.

Differential & Transfer Case Fluids

• Similar intervals to transmission fluid.

• Use the correct gear oil specified for your truck (often GL‑5 for diffs).

• Again, open the fill plug before the drain plug.

Air Filter

• Check interval: at every oil change; replace as needed.

• Tips:

  • Dirty filters hurt performance and fuel economy.

  • Some KEI filters can be matched by size to U.S. filters; others need to be imported or ordered from specialty KEI parts suppliers.

Coolant

• Interval: often every 2–5 years, depending on type.

• Use the proper type of coolant (many Japanese engines do well with phosphate‑free, silicate‑free coolants; often marketed as “Asian vehicle” coolant).

• Bleeding air is important on some mid‑engine/under‑seat layouts – follow proper procedures to avoid hot spots.

A/C Refrigerant

• Many imported KEI trucks still use R134a, but confirm with your under‑hood label.

• If your A/C isn’t cold:

  • Check for obvious leaks or oily residue at fittings and hoses.

  • Have the system vacuum tested and recharged by an A/C‑qualified shop.

  • Avoid “stop leak” products; they can cause more damage long‑term.