Royal Purple, Mobile 1 and Penzoil are top-rated brands of synthetic motor oil as of 2015, according to Injector Cleaner Boss. Other quality brands include Valvoline, Castrol and Rotella.
Royal Purple manufactures a variety of synthetic motor oils, including oils for regular cars and racing vehicles. The oils promote engine longevity and proper function.
Another top oil manufacturer, Mobile 1, also produces highly rated automotive oil filters. One of the most popular Mobile 1 products is Extended Performance oil, which requires changing at 15,000-mile intervals. Mobile 1 Extended Performance discourages engine sludge accumulation and remains stable in high heat.
Penzoil Ultra Platinum is a synthetic oil that resists thickening in low temperatures. It also reduces the risk of engine damage due to excessive heat.