How often should you change your oil in terms of time, not mileage?

I live in a city and rarely drive. Are there a certain number of months one should wait until they get an oil change? Because i'm not going to hit the 3-5,000 mile mark any time soon.|||If you seriously drive that little, I would say an absolute minimum of once per year, preferably right at the beginning of winter. The engine and the oil take the hardest "beating" in the winter (cold startups, cold air causes condensation, etc), so having fresh oil is most important through the heart of winter.



Twice a would be better, before and after winter. Don't worry about being exactly 6 months split, I bet you drive more in the winter (most folks do), so split the changes based on average daily temps. There is no absolute rule, but I would arbitrarily draw a line at average daily temps (hi+lo / 2) around freezing.



If you go with the once-per-year scenario, go synthetic oil. Twice per year, just use conventional or synthetic blend. Take into account how harsh your winters are: synthetic oil is much better at very low temps, so if you live in Minneapolis, you may want synthetic in the winter if changing twice per year; but if you live in Tampa, there is almost no reason to ever use synthetic, even changing your oil only once per year.



Some folks may say you can extend drains using synthetic, and my explanation above may even sound like that. That is not what I wish to convey. Synthetic is better, and I suggest it primarily because most wear happens at startup, and more wear happens in the winter, so synthetic makes sense. Regardless of conventional or synthetic oil, the additives in the oil are designed to sacrifice themselves to protect the engine. The oil base (synthetic or conventional) will last long past the point that all the additives get used up. Once per year is an absolute minimum, twice per year is pretty reasonable. And rotate the tires every time you change the oil (30 minutes of your own time, or $30+ at a shop).



Last bit: don't use oil additives or flushes, many oil-change places will try to sell them to you as ways to make your oil better or make your engine last longer (including "high-mileage oils" for cars with over 75,000 miles). There is no such thing as a tune-up-in-a-can, just as there are no diet pills that let you eat more and lose weight. When you take your vehicle in for an oil change, take it out for a road trip, at least an hour, so the oil is ripping hot. This cooks a lot of the water and volatiles out, and anything that doesn't burn off will be suspended in the oil and get taken out with the oil during the drain. Also, use the weight of oil recommended by the manufacturer. Some lube shops and weekend mechanics cleave to the old idea that older cars need heavier oil: again, most wear happens at startup, so use the oil the engineers designed the engine around, which, for most cars since the 1980s, is 5w20 or 5w30.



Okay, one more "last" bit: your engine oil is not the only thing to get "used up," you may need gearbox or transmission fluid changes, coolant changes, air filter, and fuel filter. From your description, I'd say check your owner's manual for miles/months for changing those fluids, but get them changed at least every 3 years. *Especially* the coolant. If you get your oil changed twice per year, plus do one other preventative maintenance item at each oil change, you will probably cycle through all of them at a reasonable interval. Not a bad idea to either keep a log, or else write dates/mileage on the replaced filter or part...|||Change your oil about every 3000 to 3500 miles.Or every 3 to 4 months.|||Every 9 months to a year.