Towing STI Vehicles
If you get questions from your customers about the proper way to tow Impreza STI vehicles behind a recreational vehicle or pickup truck, you should instruct them to tow the vehicle with all four wheels on the road, just as you would all Subaru manual transmission vehicles.
However, the STI model is equipped with the Driver Controlled Center Differential (DCCD), and must be set in Manual Mode and the DCCD control dial must be set to the farthest rearward position (see below).
Also, as with other Subaru models with manual transmissions:
- The transmission must be in the neutral position.
- Do not apply the parking brake.
- The ignition switch should be in the “ACC” position.
- All four tires should be the same size and brand. Old and new tires should not be mixed on the vehicle.
- All four tire pressures should be maintained at correct levels.
- Differential and transmission oil levels should be proper.
Note: The Subaru Impreza STI uses a unique rear LSD differential oil. Using the incorrect oil may cause premature failure. The oil recommended for the STI rear differential is Genuine Subaru LSD Gear Oil, P/N K0305Y0900, or equivalent.
Please refer to the owner’s manual for any additional information.
Safe Handling of Sodium-Filled Exhaust Valves
Subaru introduced sodium-filled exhaust valves on all 2004 model year 2.5L DOHC engines. Sodium has a high thermal conductivity and liquefies at high temperatures. Once liquefied, it moves within the valve to promote faster cooling of valve head by transferring heat to the valve stem.
Sodium is a highly alkaline substance that will react severely when exposed to moisture. Never attempt to saw or break these valves as injury may result. Metallic Sodium may cause blindness if it comes into contact with the eyes. It may also cause burns if it contacts the skin or start a fire if it contacts other chemicals.
Valves that are damaged due to accidents or other types of engine damage may expose the sodium to the atmosphere. In these cases, appropriate handling of the valves is required to avoid personal injury or property damage.
If the valve is damaged, remove it and neutralize it by immersing it in water:
- Wearing safety glasses and rubber gloves, remove the damaged valve from the cylinder head.
- Prepare a large receptacle (bucket or other container) in a well-ventilated location. Fill the receptacle with at least two gallons of clean water.
- Immerse the damaged valve in the water.
Note: A severe reaction may occur when the valve is immersed in the water, so move away quickly. Stay at least six feet away from the receptacle. Because the reaction will produce hydrogen gas, do not place the receptacle near sparks or flame.
- Once the reaction is completed (four to five hours), carefully remove the valve using pincers or tongs. Do not let the liquid touch your skin. If skin contact occurs, immediately flush the area with large quantities of water.
- Dispose of the neutralized valve along with other metal parts, according to regulations.
- The liquid from the receptacle is now a strong alkaline solution and must be disposed of according to regulations.
- Thoroughly rinse the receptacle before using it for other purposes.
When disposing of sodium-filled valves, always comply with all applicable local, state and federal hazardous materials regulations.