Auto Engines Are Continuously Improving
Automobile engines operate under extreme conditions. They are constantly burning fuel at around 1400 degrees F. They are rotating at a rate between 2000 and 5000 revolutions per minute. They are often started up at temperatures below freezing and then put into gear before they’ve had a chance to circulate the oil thoroughly. Yet through all these extremes they will last over 200,000 miles with proper maintenance.
The basic design of the four cycle internal combustion engine hasn't changed in over 100 years, but constant refinements have made it many times better. Early designs were "flat heads" with the valves in the engine block. These were replaced with overhead valve engines that contained the valves in the head. In this design the valves were opened and closed with push rods and rockers. Next came the overhead cam where the cam operated a lifter which directly operated the valve. Up until the mid 1980s most vehicles used two valves per cylinder, an intake valve and an exhaust valve. Beginning in the last half of the 80s, in order to gain efficiency and lower emissions, car makers began adding cams and valves. Now four valves per cylinder, two exhaust and two intake valves, with two camshafts per head is a common design. In order to further increase efficiency and performance, variable valve timing was introduced. Variable valve timing allows the valves to open or close with different timing to match different conditions of speed and engine load.
The materials that engines are made with have improved greatly also. Piston rings used to cause a taper in the top of the cylinder bore as material was worn away from the cylinder wall. Today this condition is rarely seen. Toyota uses a porcelain lined cylinder on some of its models. This eliminates hot spots, reduces wear and allows for better thermal efficiency.
Most Engines Will Last Over 200,000 Miles With Proper Maintenance
Things that will cause an engine to fail prematurely are:
Not changing oil at the correct intervals. If driving conditions consist of drives less than 10 miles or involve stop and go traffic, oil should be changed at 3000 miles.
Overheating. A cooling system that is not operating correctly can cause an engine to overheat (in the red zone). Driving the vehicle in this condition for any amount of time will cause serious damage.
Not paying attention to the gauges. If an oil gauge flashes or a temperature gauge moves close to the red, find out why. Don't think it will fix itself.