How long can spark plugs last? There are two types of spark plugs: conventional and long-life (platinum- or iridium-tipped). Conventional spark plugs need to be replaced every 30,000-50,000 miles. Recommended replacement intervals for iridium- or platinum-tipped spark plugs vary between 50,000 and 120,000 miles. To find out the recommended replacement interval for your car, check your maintenance schedule.
Its key principles: (1) the three primary colors are red, yellow and blue, (2) the primaries exist as three material substances (often identified with specific pigments), (3) the primaries cannot be mixed from other colors, but can mix all other colors.
SUBTRACTIVE colors are like paint. For additive colors, you can make yellow from adding red and green light. Or yellow, being a spectral color, means that light of a pure certain wavelength, around 570nm, is itself yellow. For subtractive colors, yellow indeed is a primary, and is the reason that the inks coming from most color printers are NOT red, green or blue, but rather cyan, magenta and yellow (and sometimes black).