Kei Truck Maintenance Guide: Oil, Fluids, Belts, and What to Service First

TL;DR: Change every fluid the day your truck arrives. Engine oil (2.8 to 3.1 liters depending on model), transmission fluid, differential oil, brake fluid, and coolant. Replace the timing belt if you can't verify when it was last done. Budget roughly $300 to $500 for a full first service, then $150 to $250 per year after that. These engines are simple, reliable, and cheap to maintain if you stay on schedule.

Your kei truck just came off a boat from Japan. It's got 40,000 km on the clock, the paint has that nice patina, and you're already planning where to mount the light bar. But before you do anything fun, you need to do the boring stuff first. Every fluid in that truck is old. The rubber is old. The belts are old. And because these 660cc engines have tiny oil capacities and tight tolerances, skipping maintenance hits harder than it would on a full size truck.

This is the complete kei truck maintenance guide. What to service first, what fluids and specs to use across every major model, and the ongoing schedule that keeps these trucks running for 200,000 km and beyond.

The Day One Service: What to Do When Your Truck Arrives

Forget about mods. Forget about the lift kit. The single most important thing you can do for a freshly imported kei truck is a complete fluid flush. Every fluid. No exceptions.

Here is why: most imported kei trucks are 25 to 30 years old per the 25 year import rule. Even if the odometer reads low, that vehicle has been sitting on a Japanese auction lot, in a shipping container, and on a dock. The oil has been oxidizing. The coolant has been degrading. The brake fluid has absorbed moisture. None of these fluids are protecting anything anymore.

Your Day One checklist should look like this:

Drain and replace engine oil and filter
Drain and replace transmission fluid
Drain and replace differential oil (front and rear on 4WD models)
Flush and replace brake fluid
Drain and replace coolant
Inspect timing belt (replace if service history is unknown)
Inspect all accessory belts and replace if cracked
Check all rubber hoses for cracking or swelling
Inspect CV boots for tears
Check spark plugs and replace if fouled
Grease all chassis lube points
Check tire pressure (28 to 29 PSI is standard for most models)

That is a full day of work in the driveway. It is also the single best insurance policy you can buy for your truck. Total parts cost runs $300 to $500 depending on the model and whether you need a timing belt kit. If you are paying a shop, expect $600 to $1,000 for the full service.

If you haven't bought your truck yet, our pre-purchase checklist covers what to inspect before money changes hands.

Engine Oil: Types, Capacities, and Intervals by Model

Kei truck engines are small. Really small. That 660cc three cylinder holds less than a gallon of oil in most cases. This means the oil works harder, gets hotter faster, and degrades quicker than oil in a bigger engine. Short change intervals are not optional on these trucks.

Here is the breakdown by model:

Suzuki Carry (F6A / K6A Engines)

The Carry is the most common kei truck in the US, and the easiest to find parts for. The F6A engine (found in the DC51T and DD51T chassis from 1991 to 1999) takes 3.1 liters of oil with a filter change. The recommended weight is 10W30 for most climates. Drop to 5W30 if you're dealing with temperatures below about 15 degrees Fahrenheit.

Oil capacity: 3.1 liters (with filter)
Oil weight: 10W30 (summer/general), 5W30 (cold climates)
Oil filter: Fram PH4967 or equivalent
Change interval: Every 5,000 km (3,100 miles) or 6 months
Spark plugs: NGK DCPR7E, gap 0.8 to 0.9mm

The transmission takes 1.1 liters of 75W90 GL4 gear oil, changed every 20,000 km or two years. Differential oil is 75W80 GL5, about 1 liter, same interval. Coolant capacity is 4.7 liters. Use a quality ethylene glycol Asian vehicle coolant and flush every two years.

Honda Acty (E07A Engine)

The Acty's E07A is one of the more refined kei truck engines, and Honda's reputation for engineering holds up here. Oil capacity is 2.9 liters with a filter change, or about 2.7 liters without. Honda's factory recommendation is 10W30 for normal driving, with 5W30 for temperatures below minus 22 degrees Fahrenheit.

Oil capacity: 2.9 liters (with filter)
Oil weight: 10W30 (standard), 5W30 (cold climates)
Oil filter: NAPA 1334, NAPA Gold 1358, Fram PH9688, or Mobil 1 M1-108A (M20x1.5 thread)
Change interval: Every 5,000 km (3,100 miles) or 6 months
Spark plugs: NGK BKR6E

Honda's factory manual actually lists a 10,000 km oil change interval, but that assumes Japanese driving conditions with frequent short trips that keep the engine warm. For US use, especially if you're running your Acty on dirt roads, farms, or in dusty conditions, cut that in half. Stick with 5,000 km.

Daihatsu Hijet (EF Series Engines)

The Hijet uses Daihatsu's EF series engines across its production run. The S110P (660cc, mid 1990s) is the most commonly imported version. Oil specs are similar to the other kei trucks: 10W30 or 10W40 for general use, with about 3 liters capacity including the filter.

Oil capacity: Approximately 3.0 liters (with filter, verify against your service manual as EF variants differ)
Oil weight: 10W30, 10W40, or 5W30 (cold climates)
Oil filter: Wix 51394, Walmart SuperTech ST7317
Change interval: Every 5,000 km (3,100 miles) or 6 months
Spark plugs: Denso K20PR-U11 or Autolite 64, gap 0.035 inches

For the 4WD Hijet, the front differential takes about 0.83 quarts of 80W90, and the rear takes about 1.34 quarts of 90W gear oil. Transmission and transfer case both use 75W85 GL4 gear oil. One quirk with the Hijet: the transmission fill plug can be incredibly difficult to access. Some owners weld a 14mm nut onto the filler cap so they can get a box end wrench on it. Worth considering if you're doing the job on your back without a lift.

Subaru Sambar (EN07 Engine)

The Sambar is a rear engine, rear wheel drive (or AWD) layout, which makes oil changes a bit different from the other trucks. Pop the rear bumper open and the dipstick and fill cap are right there. The drain plug is on the underside of the oil pan, accessible from in front of the rear wheel with a 14mm socket.

Oil capacity: Approximately 2.8 to 3.0 liters (with filter, verify with dipstick as EN07 variants differ)
Oil weight: 5W30 synthetic recommended. Some owners run 5W40 (Shell Rotella T6 is a popular choice)
Oil filter: Wix 51356, Pro-tec PTL51356/165, or Bosch ST3300 (cross references to early 1990s Subaru Justy filters)
Change interval: Every 5,000 km (3,100 miles) or 6 months

The Sambar's 5-speed manual transmission takes about 2.2 liters of 75W90 GL4 gear oil (Redline MT90 is a solid choice). The rear differential is integrated into the transmission, so no separate service is needed. The front differential on AWD models takes about 1 quart of 75W90 GL5 oil. Both drain and fill plugs on the front diff are 17mm.

Mitsubishi Minicab (3G83 Engine)

The Minicab's 660cc 3G83 engine (produced from 1990 to 2014) shares similar maintenance specs with the rest of the kei truck lineup. Oil capacity is approximately 2.9 quarts without the filter, closer to 3.4 quarts with a filter change.

Oil capacity: 3.2 liters / 3.4 quarts (with filter)
Oil weight: 10W30 or 10W40 (summer), 5W30 (winter)
Oil filter: Wix 51356, NAPA 1356, Fram 1365
Change interval: Every 5,000 km (3,100 miles) or 6 months
Spark plugs: NGK BKR6E or Denso K20PR-U11

For 4WD Minicabs, the manual transmission takes about 2.5 pints (1.2 liters) of 75W85 GL4 gear oil. Front axle holds 1.5 pints (0.75 liters) and the rear axle takes 2.3 pints (1.15 liters) of 85W90. Brake fluid is DOT 3, and the coolant system holds 3.9 quarts including the heater core and reserve tank.

The Timing Belt: The One Job You Cannot Skip

Every kei truck engine uses a timing belt, and every one of them needs replacement at regular intervals. As Hagerty and every kei truck mechanic will tell you, this is the single highest stakes maintenance item on these trucks. Most of these engines are interference designs, meaning if the belt snaps, the pistons hit the valves, and you're looking at a full engine rebuild or replacement.

The factory interval across most kei truck models is 100,000 km (about 62,000 miles) or 10 years, whichever comes first. Here is the critical part: if you just imported a 1995 truck with 50,000 km on it, that belt is over 30 years old. Rubber degrades with age regardless of mileage. Replace it. Do not gamble on a decades old belt to save $100.

A timing belt kit for most kei trucks runs $45 to $120 depending on the model and whether you're buying OEM from Amayama or aftermarket. The kit typically includes the belt, tensioner, and idler pulleys. While you're in there, replace the water pump too. It's driven by the timing belt on most of these engines, and if the water pump seizes after you've buttoned everything back up, you're pulling it all apart again.

One notable exception: the Subaru Sambar's EN07 engine is a non interference design, meaning a belt failure won't destroy the valves. Even so, a broken timing belt still leaves you stranded, so replace it on schedule regardless.

For timing belt kits and other critical OEM parts, check our parts sourcing guide for the best suppliers.

Rubber Components: The Silent Killers

After 25 to 30 years, every rubber component on your kei truck is suspect. The Drive has covered this in the context of JDM imports, and the advice applies doubly to kei trucks. Coolant hoses, vacuum lines, CV boots, motor mounts, and brake hoses all degrade with age. They get hard, crack, and fail. Sometimes gradually, sometimes all at once on a highway on ramp.

Inspect every rubber hose and boot during your Day One service. Replace anything that's cracked, swollen, or rock hard when you squeeze it. Pay special attention to:

Coolant hoses: Upper and lower radiator hoses, plus heater hoses. A burst hose on a 660cc engine will overheat the motor in minutes
CV boots: Check the inner and outer boots on all drive axles. Torn boots let grease escape and dirt in, which destroys the CV joint. A $15 boot replacement prevents a $200 axle replacement
Vacuum lines: Cracked vacuum lines cause rough idle, poor fuel economy, and erratic behavior from vacuum operated components
Motor mounts: Rubber motor mounts get soft and collapse over time. If the engine shifts noticeably when you blip the throttle, the mounts are toast

Most of these parts are cheap. A full set of coolant hoses might run $30 to $60 from Megazip or a kei truck parts specialist. The labor is the real cost, but it's straightforward wrench work on engines this simple.

The Ongoing Maintenance Schedule

Once you've knocked out the Day One service, maintaining a kei truck is genuinely easy. These engines have no complicated variable valve timing, no turbo plumbing (on most models), no direct injection, and no emissions equipment to deal with. It's a carburetor or basic fuel injection, a distributor, and three cylinders. Your grandfather could work on this motor.

Here is the ongoing schedule:

Service Item	Interval	Notes
Engine oil and filter	Every 5,000 km / 6 months	Use 10W30 or 5W30 depending on climate
Air filter	Every 10,000 km / 12 months	Check more often in dusty conditions
Spark plugs	Every 20,000 km / 24 months	NGK or Denso only
Transmission fluid	Every 20,000 km / 24 months	75W90 GL4 for most models
Differential oil	Every 20,000 km / 24 months	Check your model's specific GL rating
Brake fluid	Every 24 months	DOT 3 or DOT 4 depending on model
Coolant	Every 24 months	Ethylene glycol, Asian vehicle formula
Timing belt	Every 100,000 km / 10 years	Replace water pump at the same time
Accessory belts	Inspect every 10,000 km	Replace at first sign of cracking or glazing
Tire rotation	Every 5,000 km	Front to back on 2WD, cross pattern on 4WD

Most owners on r/keitruck and r/minitrucks report annual maintenance costs settling around $150 to $250 once the initial catch up service is done. That's filters, oil, and the occasional belt or hose. Cheaper than maintaining a riding lawn mower in some cases.

Where to Find Parts and Specs

Finding the right parts and the right specs is half the battle with kei truck maintenance. Your chassis code is the key to everything. It's stamped on the firewall plate and printed on your Japanese export certificate. Every parts lookup starts there.

For OEM parts shipped from Japan, Amayama is the best source. Search by chassis code and get genuine manufacturer parts with correct fitment. For parts diagrams and part number lookups, Megazip has exploded diagrams of every assembly on every kei truck model. Find the part number on Megazip, then order from wherever has the best price.

For cross compatible filters, belts, and brake components that are already sitting on shelves at your local auto parts store, our parts sourcing guide has the complete breakdown of which domestic part numbers match which kei truck models.

The MiniTruckTalk forum is an invaluable resource for model specific maintenance questions. Decades of owner experience are archived there, including fluid capacities, part numbers, and tips that never made it into any service manual.

Common Mistakes to Avoid

A few things trip up new kei truck owners on maintenance, and the NHTSA import guidelines won't warn you about any of them:

Using GL5 gear oil in the transmission. GL5 has additives that attack brass synchro rings. Use GL4 for manual transmissions and transfer cases. GL5 is fine for differentials only
Overfilling the engine oil. These engines have small sumps. Even half a quart too much can cause oil to blow past seals or get whipped into foam by the crankshaft. Use the dipstick, not the capacity spec, as your final check
Ignoring the timing belt because the mileage is low. Time kills belts just as much as mileage. A 30-year-old belt with 40,000 km on it is more dangerous than a 5-year-old belt with 90,000 km
Skipping the water pump during timing belt service. The water pump is right there behind the timing belt. Replacing it adds $30 to $50 in parts and 15 minutes of labor. Not replacing it means pulling the whole front of the engine apart again when it fails next year
Using the wrong coolant. Japanese engines are designed for specific coolant chemistries. Use an Asian vehicle formula (phosphate based) rather than standard US "universal" green coolant, which uses silicate chemistry that can damage Japanese aluminum components over time

The Bottom Line

Kei truck maintenance is simple, cheap, and straightforward. These are 660cc three cylinder engines with mechanical simplicity that modern trucks lost decades ago. The key is staying on top of it, because the small oil capacities and tight tolerances mean neglect shows up faster than it would on a bigger motor.

Do the full fluid flush and inspection when your truck arrives. Replace the timing belt if there's any doubt about its age. Then stick to the schedule: oil every 5,000 km, fluids every two years, and timing belt every 100,000 km or 10 years. That's it. Your kei truck will run for years on a maintenance budget that wouldn't cover two oil changes on a modern full size pickup.

Parts are available if you know where to look. The community is active and helpful. And working on an engine you can literally see over in one glance is a welcome change from crawling under a modern truck just to find the oil filter. Once you have got the mechanical side sorted, tackle rust prevention next. Make sure your insurance covers the truck at agreed value, and browse our dealer directory if you need a shop that knows these trucks. If you are still shopping, our import cost calculator estimates your total landed cost including state fees. These trucks reward owners who maintain them. Be that owner.