Car care · Elgin Auto Sales & Service Center · Elgin, IL
How to Check Coolant
Engine coolant (antifreeze) keeps your engine from overheating in summer and freezing in winter. Checking the level takes a minute, but only if you do it the safe way: with the engine cold and the pressure cap left alone. This guide walks through the check, what the marks mean, what to look for, and when to let a technician take over.
Engine coldthe only time to check the level
MIN to MAXwhere the level should sit on the bottle
Once a monthRam's check interval for the coolant bottle
Every 12 monthsRam's antifreeze protection check
The short answer
Park on level ground and let the engine cool completely. Open the hood, find the plastic coolant bottle (reservoir) and read the level against its MIN and MAX marks without opening the radiator or the pressure cap. If the level is below MIN, add only the coolant type your owner's manual specifies, or have a shop do it. Never open a cooling system pressure cap when the engine is hot.
Safety first: only check a cold engine
The cooling system runs hot and under pressure. Using Ram's 2026 owner's manual as an example:
- Hot coolant or steam can cause serious burns. If you see or hear steam coming from under the hood, do not open the hood until the radiator has had time to cool.
- Never open a cooling system pressure cap when the radiator or coolant bottle is hot, and do not loosen or remove the cap to cool an overheated engine.
- Never add coolant when the engine is overheated.
- Keep hands, tools, clothing and jewelry away from the radiator cooling fan. It is temperature controlled and can start at any time, even with the engine off.
From the 2026 Ram 1500 Owner's Manual (Cooling System warnings; Cooling System Pressure Cap), read November 3, 2026. Check your own owner's manual for your vehicle's warnings.
How to check coolant, step by step
1. Park and let it cool
Park on level ground, turn the engine off and wait until the engine is cold. The level should be read with the engine cold.
2. Find the coolant bottle
Open the hood and find the coolant bottle, also called the reservoir or expansion bottle. Your owner's manual's engine compartment diagram shows where it is.
3. Read the marks
Ram's manual says the coolant level in the bottle should be between the MIN and MAX range when the engine is cold.
4. Leave the radiator cap on
Ram notes the radiator normally stays completely full, so there is no need to remove its cap unless you are checking the freeze point or replacing coolant.
5. Look around
While the hood is up, look at the hoses and the front of the radiator (see below).
6. Close up and decide
If the level is between the marks, you are done. If it is low, see the next sections before adding anything.
Steps 3 and 4 are from the 2026 Ram 1500 Owner's Manual (Checking Coolant Level), read November 3, 2026. Ram's level-check instructions are written for its 3.6L engine; bottle location and markings vary by vehicle.
What to look for while the hood is up
Ram's manual lists these cooling system checks:
- Coolant condition: if the coolant looks dirty or rusty, or contains visible sediment, the system should be drained, flushed and refilled with fresh coolant.
- Hoses: check the cooling system hoses for brittle rubber, cracking, tears, cuts and tight connections at the coolant recovery bottle and the radiator.
- Leaks: inspect the entire system for leaks.
- Debris: check the front of the A/C condenser (if equipped) or radiator for bugs and leaves; if dirty, clean it by gently spraying water from a garden hose vertically down the face of the A/C condenser or the back of the radiator core.
- Pressure cap: Ram says the cap must be fully tightened and should be inspected and cleaned if foreign material builds up on its sealing surfaces.
From the 2026 Ram 1500 Owner's Manual (Engine Coolant Checks; Cooling System Pressure Cap), read November 3, 2026.
If the coolant is low
A low level means coolant has to be added, and if it keeps happening, something is wrong. Ram's guidance:
- Add coolant to the coolant bottle, not the radiator, and do not overfill.
- Use the coolant your manual specifies. The 2026 Ram 1500 uses OAT coolant meeting Material Standard MS.90032; Ram says mixing coolant types is not recommended and can damage the cooling system.
- Do not use water alone or alcohol-based coolant, and do not add rust inhibitors or anti-rust products.
- Some vehicles require special tools to add coolant properly, and filling them incorrectly could cause severe engine damage. Ram says to contact an authorized dealer if coolant needs to be added to those vehicles.
- If frequent coolant additions are needed, Ram says the cooling system should be pressure tested for leaks.
From the 2026 Ram 1500 Owner's Manual (Adding Coolant; Selection Of Coolant notes; Checking Coolant Level; Cooling System Notes), read November 3, 2026. Coolant types differ by vehicle; check your own owner's manual.
How often to check your coolant
Ram lists the coolant fluid reservoir among the checks to make once a month or before a long trip, and says that as long as the engine operating temperature is satisfactory, the coolant bottle need only be checked once a month. Ram also says to check the antifreeze protection every 12 months, before freezing weather where that applies.
For the 2026 Ram 1500, Ram's maintenance plan calls for flushing and replacing the engine coolant at 10 years or 150,000 miles, whichever comes first. Other vehicles have different intervals, so check your own manual.
From the 2026 Ram 1500 Owner's Manual (Once A Month Or Before A Long Trip; Engine Coolant Checks; Checking Coolant Level; Adding Coolant; Maintenance Plan), read November 3, 2026.
Cooling system service at Elgin Auto Sales & Service Center
We service all makes and models. If your coolant is low, looks dirty, or you keep having to top it off, bring the car in and we can inspect the cooling system. Coolant flushes are among the services you can request online.
Our service department at 1200 E. Chicago St. in Elgin is open Monday to Friday 8 a.m. to 5 p.m. and Saturday 8 a.m. to 4 p.m., and is closed Sunday. Schedule service, see our service specials or get directions.
Checking coolant FAQ
Should I check coolant with the engine hot or cold?
Cold. Ram says the level should be read with the engine cold, and never to open a cooling system pressure cap when the radiator or coolant bottle is hot.
Where should the coolant level be?
Between the MIN and MAX marks on the coolant bottle when the engine is cold, according to Ram's manual. Check your own manual for your vehicle's markings.
Do I need to open the radiator cap to check coolant?
No. Ram says the radiator normally stays completely full, so there is no need to remove its cap unless you are checking the freeze point or replacing coolant. Read the level on the coolant bottle instead.
How often should I check my coolant?
Ram says the coolant bottle need only be checked once a month as long as the engine temperature is normal, and lists the coolant reservoir among the checks to make before a long trip.
Can I add water instead of coolant?
Ram says not to use water alone. Use the coolant type your owner's manual specifies, mixed as the manual directs.
Why does my coolant keep getting low?
Coolant should not keep disappearing. Ram says that if frequent coolant additions are required, the cooling system should be pressure tested for leaks.
Coolant low or looking dirty?
Schedule a cooling system check at 1200 E. Chicago St. in Elgin. We service all makes and models.
Sources
Safety warnings, the level check, inspection points, coolant guidance and intervals are from Ram's 2026 Ram 1500 owner's manual, read on November 3, 2026. We cite one automaker's manual as an example; coolant types, bottle markings and intervals differ by vehicle, so check your own owner's manual. Our address, hours and service list are from our own website, checked the same day. Photo is of our dealership.
- 2026 Ram 1500 Owner's Manual (Cooling System; Engine Coolant Checks; Adding Coolant; Checking Coolant Level; Maintenance Plan), Mopar
- Service department and service hours, Elgin Auto Sales & Service Center
- Home page: address, Elgin Auto Sales & Service Center