Originally Posted By birdbarian:
I am one of the lucky few who does not drive that much on a regular basis. I can go six months or longer before I hit 3k miles on my car. Is it harmful to wait until I get to 3k miles, or is it significantly better to do it at 3 months eventhough I may have only driven 1500 miles? I drive a 7 mile loop to work with just a few stop lights. On the way to work, I get up to highway speeds for a mile or so.
How often you should change your oil depends on several factors.
1. What does your manufacturer reccomend as an OCI?
2. What kind of conditions do you drive in? (Dusty/dirty, etc...)
3. How do you run your engine? (high RPMs, towing, etc...)
4. Does your engine have known sludge problems?
The 3,000 mile interval is a pretty good one for most applications. It is erring on the side of engine safety. I haven't met anyone who has ruined an engine by changing the oil every 3,000 miles.
That being said, the 3,000 mile interval is far less than most modern oils are capable of. Full synthetics like Mobil 1 can really go into the 10,000 mile range without the oil itself breaking down or loosing any lubrication qualities whatsoever under the right conditions. The oil does, however, get dirty as the oil filter can only absorb so much gunk. How much the filter can absorb depends on the filter that you use. I am personally fond of Pure One and K&N oil filters, as they do a good job of filtering. Other brands do a decent job too, but the el-cheapo Frams should be avoided.
I drive my car pretty easily in a relatively clean environment. I rarely go above 2,000 RPMS for anything, and I never tow anything. I use Mobil 1 full synthetic and thus really don't need to change my oil very often at all. I change it every 5,000 miles or so simply because I want to make sure I have an oil filter that can still filter. The oil itself is usually still in great condition around then.
If I was in an environment with lots of dust/sand/blowing grit, I would change my oil more frequently. If I towed, I would change my oil more frequently. Same if I ran my engine hard.
The more you ask of your engine, the more often you should change your oil.
If, however, you don't drive your car in those demanding conditions, then use a good quality synthetic and filter, and you can probably go 5,000 miles or more between changes.