Synthetic car oil needs to be changed after 10,000 to 20,000 miles, depending on the climate and driving distances. The recommended non-synthetic oil change is every 3 months or 3,000 miles, whichever comes first. However, synthetic oils, which cost nearly twice as much as conventional oils, require less time between changes because of their ability to withstand high temperature levels.
According to a spokesman for Planet Green, synthetic oils last up to three times longer than conventional oils. Environmentally, synthetic oils contribute chemicals too, but 15 to 24 quarts are saved yearly from being dumped. Synthetics burn cleaner with a lower volatility, which slows exhaust evaporation.