2003 Toyota Sequoia Owners Manual - Page 288

03_SEQUOIA_U (L/O 0209) Brake system D Oil is also used to lubricate the stems of the intake valves. Some of this oil is sucked into the combustion chamber together with the intake air and is burned along with the fuel. High temperature exhaust gases also burn the oil used to lubricate the exhaust valve stems. The amount of engine oil consumed depends on the viscosity of the oil, the quality of the oil and the conditions the vehicle is driven under. More oil is consumed by high−speed driving and frequent acceleration and deceleration. A new engine consumes more oil, since its pistons, piston rings and cylinder walls have not become conditioned. When judging the amount of oil consumption, note that the oil may become diluted and make it difficult to judge the true level accurately. As an example, if a vehicle is used for repeated short trips, and consumes a normal amount of oil, the dipstick may not show any drop in the oil level at all, even after 1000 km (600 miles) or more. This is because the oil is gradually becoming diluted with fuel or moisture, making it appear that the oil level has not changed. The diluting ingredients evaporate out when the vehicle is then driven at high speeds, as on an expressway, making it appear that oil is excessively consumed after driving at high speeds. IMPORTANCE OF ENGINE OIL LEVEL CHECK One of the most important points in proper vehicle maintenance is to keep the engine oil at the optimum level so that oil function will not be impaired. Therefore, it is essential that the oil level be checked regularly. Toyota recommends that the oil level be checked every time you refuel the vehicle. The tandem master cylinder brake system is a hydraulic system with two separate sub−systems. If either sub−system should fail, the other will still work. However, the pedal will be harder to press, and your stopping distance will be longer. Also, the brake system warning light may come on. CAUTION Do not drive your vehicle with only a single brake system. Have your brakes fixed immediately. BRAKE BOOSTER The brake booster uses engine vacuum to power −assist the brakes. If the engine should quit while you are driving, you can bring the vehicle to a stop with normal pedal pressure. There is enough reserved vacuum for one or two stops-but no more! NOTICE Failure to check the oil level regularly could lead to serious engine trouble due to insufficient oil. For detailed information on oil level check, see "Checking the engine oil level" on page 358 in Section 7 −2. 288 2003 SEQUOIA from. Sep. '02 Prod. (OM34420U)