For 1990-2009 cars

Caution: This vehicle is equipped with a Supplemental Inflatable Restraint (SIR) System. Failure to follow the correct procedure could cause the following conditions:

• | Air bag deployment

• | Personal injury

• | Unnecessary SIR system repairs

In order to avoid the above conditions, observe the following guidelines:

• | Refer to SIR Component Views in order to determine if you are performing service on or near the SIR components or the SIR wiring.

• | If you are performing service on or near the SIR components or the SIR wiring, disable the SIR system. Refer to Disabling the SIR System.

Caution: NEVER spray water on a hot heat exchanger. The resulting steam could cause personal injury.

NOTICE: When adding coolant, it is important that you use GM Goodwrench DEX-COOL® or HAVOLINE® DEX-COOL® coolant. If Coolant other than DEX-COOL® or HAVOLINE® DEX-COOL® is added to the system the engine coolant will require change sooner; at 50 000 km (30,000 mi) or 24 months.

Regular maintenance of the cooling system will help it operate properly. Check the cooling system at least once a year with the following procedures.

Drain and refill the cooling system every five years or 240 000 km (150,000 miles).

### Checking the Coolant

Remove the reservoir cap in order to check the coolant level. This is shown on the coolant overflow hose visual indicator.

Check the coolant level in the recovery reservoir every time the hood is up and the engine coolant is cold.

The level should be near the COLD mark when the system is cold. The coolant level should rise when the vehicle is at normal operating temperature. Add coolant to the recovery reservoir only in order to raise the level to the COLD mark.

Check the color of the coolant while draining the system. If the coolant shows an unusual amount of oil sediment (gray, white, or foamy appearance), engine oil may be leaking into the cooling system. A coating of oil on the inside of the coolant passages reduces the efficiency of the system and may cause engine overheating. Also, a leak in the cooling system may cause coolant to flow into oil passages. This could contaminate the lubricant and damage the engine. If needed, check the oil condition and the oil level. Refer to Maintenance and Lubrication in General Information.

The coolant will boil under the following conditions:

• | The pressure in the cooling system is low

• | The coolant does not contain ethylene glycol antifreeze

Pure water could boil at 119°C (247°F) even with a 124 kPa (18 psi) in the cooling system. Pure water lacks the necessary rust inhibitors and coolant pump lubricant.

Do not operate the engine when the pressure cap is loose or removed unless work is being performed on the maintenance system.

### Coolant Concentration Testers

Due to a shortage of ethylene glycol, some coolant manufacturers have started to mix other types of glycol into their coolant formulations. Propylene glycol is the most common new ingredient. When a mixture other than ethylene glycol and water is being tested, a hydrometer may give an inaccurate reading. The degree of inaccuracy will vary, depending on the proportion of other glycols present in the coolant.

All GM vehicles are produced with coolant that can be accurately measured with a hydrometer. Use a refractometer to measure the coolant when the type and quality of the coolant being measured is unknown.

The following coolant testers can be used to check the antifreeze protection of the coolant:

• | J 26568 .

• | J 23688 .

Make sure that the markings on the refractometer are correct.

Test the temperature at which the J 26568 or the J 23688 is calibrated, unless the Coolant Tester has a provision for temperature correction. If the coolant is warmer or cooler, the reading may be incorrect. Follow the manufacturer's directions for using the J 26568 or the J 23688 .

### Calibrating Testers

J 26568 (Centigrade Scale) or J 23688 (Fahrenheit Scale) are factory calibrated and sealed and should not require adjustment. If adjustment is required, follow manufacturer's instructions.