One of BMW's longest running model lines, the 3-series has been around since 1975. The 2001 BMW 325i is a "saloon"-style, four-door sedan. It features a 2.5-litre, 184-horsepower engine.
According to the user's manual for the 2001 325i, the total oil capacity for the car is 7 qts. (6.62 litres). This total capacity also takes into account the half-quart required to fill the vehicle's oil filter. As such, in some places the total capacity will be listed as 6.5 quarts (6.15 litres), but this number does not include the oil required to fill the filter.
According to the user's manual, BMW recommends its own (BMW) 5W-30 High Performance Synthetic motor oil. If that oil is not readily available, the manual also recommends Valvoline SynTech, Castrol/Mobil 1 or any other synthetic motor oil provided that it is rated "API SH" or higher.
In its original marketing material, BMW suggested that new 325i owners could wait until up to 15,000 miles between oil changes. According the experts at E46 Fanatics, a website dedicated to the 3-series, this recommendation could cause mechanical problems as the oil filter included with new 2001 325i cars was not built to last 15,000 miles. As such, many owners found that by the time they brought their vehicles in for an oil change at 15,000 miles, the filter itself had begun to disintegrate. BMW has since designed a new oil filter that it says can last the 15,000 miles between recommended oil changes.