If this makes you feel better, I have never been too caught up in oil changes by an exact amount of miles ( kms ). I make sure to not let them go past 6 months, or past 9000 kms ( about 5500 miles ) but I change it more when I have the time, and in the mood to climb under the truck and do it. On my current Ram its been changed as early as 6,000 kms and as late as 8,500 kms. So if you were to get to 4,000 miles in your case, you're still golden. In my opinion worse than the actual mileage on oil, within reason of course, is those people who always just drive very short hops, and never get their vehicles warmed up, and those who idle excessively. Also don't just say well I only drive a thousand miles a year, so I can just change it every 3 years. My pickup usually does a moderate distance most of the time, as I drove 17 kms to work, just went on drives for something to do, would hook onto the snowmobile trailer and haul it 2 hours to go snowmobiling, that sort of thing. Short hops were only things like grocery shopping which is just a 5 minute drive from the house. I don't tell people how often they need to change their oil, its not my truck, so not my concern...but if you extend to 3500 miles instead of 3000, you're not going to hurt it at all unless you only drive a maximum of 2 miles per trip so it never gets warmed up, then maybe change it every 1500 miles lol
Ps. I just buy a half dozen oil filters at a time, and keep them on the shelf in the garage, buy lots of oil when its on sale, because I am cheap and hate paying full price for it, only to see it on sale for 40% off a month later. So since its usually on a good sale 3 or 4 times a year, when I see it I'll buy a years worth or so. I not only buy the drain plug washers in bulk, but just incase I ever mess up the plug I actually have a spare sitting on the shelf. People tell me I am OCD, maybe I am.
