How much coolant does a 1998 Lexus LS400 take?
The 1998 Lexus LS400 typically requires about 12 quarts (roughly 11.4 liters) of coolant for a full system fill, using a 50/50 mix of coolant and distilled water. Actual capacity can vary slightly due to heater-core drainage, aftermarket components, or subtle model-year differences. This article explains the figure and how to refill it correctly.
What the cooling system capacity covers
The total coolant capacity refers to every passage that carries coolant in the engine’s cooling loop, including the radiator, engine block, heater core, hoses, and the expansion/reservoir. Understanding what’s included helps when planning a flush or full refill.
- Radiator and radiator hoses
- Engine block passages and cylinder heads
- Thermostat housing and water pump connections
- Heater core and its supply/return hoses
- Expansion/overflow reservoir and cap assembly
- Any additional bypass lines or loops in the cooling circuit
Note: Real-world capacity can vary slightly depending on model specifics, cooling-system revisions, or whether the heater core has been drained during service. For most LS400s, planning for roughly 12 quarts (about 11.4 liters) is a safe target when performing a full drain and fill.
How to refill and bleed the cooling system
To prevent air pockets and overheating, follow a careful refilling and bleeding procedure after draining or replacing coolant.
- Ensure the engine is completely cool before starting the refill process to avoid burns and pressure hazards.
- Mix coolant to 50/50 with distilled water unless you are using Toyota Genuine Long-Life Coolant, which may be premixed to the recommended ratio.
- Fill the radiator or the expansion reservoir with the prepared mixture until fluid appears at the neck, then secure the cap or reseal the reservoir as directed in the service manual.
- With the radiator cap removed (if applicable) and the heater set to maximum heat, start the engine and let it reach operating temperature to help purge air from the heater core.
- Monitor the level and the temperature, adding more coolant as needed to maintain proper level while the system burps air.
- After the engine cools, recheck coolant levels and look for leaks around hoses, the radiator, and the water pump area; top off if necessary.
Following a systematic refilling and bleeding procedure helps ensure the cooling system operates reliably and minimizes the risk of overheating.
Summary
For a 1998 Lexus LS400, plan for approximately 12 quarts (about 11.4 liters) of coolant for a full system fill, including the radiator, heater core, and related passages, with a 50/50 mix of coolant and distilled water. Use the proper Toyota-approved coolant or an equivalent HOAT-type coolant, and follow a careful cooling-system bleed procedure after draining to prevent air pockets and overheating.
