When oil is changed a few hundred miles before 10,000, is the next change due under the warranty at exactly 15,000 (tires only, no oil) or at a sliding number 5000 past the actual mileage when the last service was done? The dealer always puts a little sticker note on with this sliding number when serviced, but if this is followed eventually one will move back an entire 5000 mi. I wonder what the warranty actually requires, as the book notes everything in absolute amounts, 5, 10, 15 etc. It gets more confusing because of limited driving a bit less than 10K mi per year, with their 6 mo and annual perdiodic service requirements, getting out of sync with their mileage requirements.
I wouldn't worry about a few hundred miles one way or the other. But, to answer your question, since Toyota's maintenance intervals call for X miles or Y months--whichever comes first--if you were to have an oil service at, say, 2K miles, the next scheduled oil service would be 10K miles or 12 moths later, whichever came first.
It is which ever occurs first, miles or time. If you get your "15,000" miles service at 13,567 miles because you timed out, then your "20,000" mile service is due at 18,567 miles or 6 months from your last service, whichever occurs first.
To further muddy the waters, manufactures also stipulate different intervals/times if you drive under "severe" conditions. These are sometimes noted as Schedule A and B in an owners manual or a series of *footnotes at the bottom of the chart.
I did our first oil change at around 7000 km and 6 months (Canadian interval is 8000 km or 6 mo). I'm inclined to not deduct that 1000 km from the next "targets", ie: my next two benchposts will still be 16000 km or 12 mo (not 15000 or 6 mo). I'm not sure if that's right, but it seems plausable. Luckily the two values are running neck-and-neck for us.
I think in your example the next service would be due 10K miles (or 1 year whichever is first) from the last oil change +or- a few hundred miles. If your last oil change was at 10,612 miles (for example) the next one would be due at 20,612 miles. The mileage at the non-oil change service would not be a factor. Since the only thing they really do at the non-oil change interval is rotate the tires and look at a couple of things it can be skipped. You can look at whatever it is you are suppose to inspect yourself, just keep a record. Tire rotations only effect the tire warranty and tire warranties are normally no good anyway. I think 5K is to frequent for tire rotation, you can look at the tread wear or measure it at 5K intervals and have the tires rotated every 10K or 20K miles, or maybe never.
Now that that I've thought about it a bit more, I have to agree with you. Logic pervails. My situation: The Canadian oil change interval is: every 8000 kilometers or 6 months For me, 6 mo came first, with odometer at (roughly) 7000 km. Now I'm at 14600 km, and about 10.5 mo. In maybe another couple of weeks it'll likely hit 15000km, which is 8000 km more than the last change, so I guess that governs.
