That's pretty darn good if you ask me. Do you notice any breakdown in the oil after 10,000 miles, or does it look like it could go longer? When I do the change around 5,000, the oil is definitely darker, but still seems to retain a good viscosity.

 

a quick analysis of the oil would tell you.

 

Dark colored oil has absolutely zero to do with whether an oil is suitable for continued use. The thing is, some oils darken within the first couple thousand miles and yet are easily good for fifteen thousand or more, while other oils stay clear amber colored and yet have long since been exhausted. For my part, I've run a dozen or so UOAs on my cars over the years, and I have yet to have a UOA indicate even 12,000 miles was too many miles.

Based upon my UOAs, changing a full synthetic oil after only 5,000 miles is throwing away good oil.

 

Simple oil test with TBN in a lab like https://www.blackstone-labs.com/
Will tell you all about oil quality and TBN will tel if you have anything left in oil what protects your engine. Is about 35$ and they send you a very nice kit.

 

We have about 13,000 miles on our CX-5 and our driving is about 90% around town. After our last service, the dealer said to bring it back either 5/16/18 or at 15,000 miles. The dealer has been pretty good with us on this car and we've not paid for any maintenance yet. Based on my situation, would anyone take their car in now or wait for the 15,000-mile mark?

 

City driving is very hard on engines, especially if its a short trips or stop and go.

Because dealer has to pay, they can tell you come back in 20K intervals.

Modern engines will last till the warranty mark, and a little bit after it. If you are planning to keep the car longer than that I would do oil sample and send it to the lab and ask to check TBN oil additives.

 

Hmmm, not sure what prompted such a comment, but with few exceptions (the 2.3 liter engine in the Gen 1 Mazda3 comes to mind), modern engines are typically good to go for hundreds of thousands of miles with just the normal maintenance recommended in the Owner's Manual.

 

So why they don't?
Less and less cars can last 150K miles major troubles free.
New engines have crazy number of sensors, each manufacturer trying to get as many MPG as possible by using oil which can get extra mile but kill engine. New complicated car exhaust systems very expensive to fix. Old cars were simple, everything simple works all new and complicated not. Look Honda and Acura, 6 speed trany lasted forever, new 9 speed can't pass 20-30K. Numbers issues, still in some cases are not fixed, good it fails before warranty ends.

Can they last longer, sure they can, question how much it will be to keep them going.

If you google, you will find financial analyses, there is a sweet spot 6-8 years, thus is how much time manufacturer want your car last, if it last longer they loosing money. And 6-8 years, people think its a good term and considering brand as reliable.

If you want your cal last longer, you need to do more than just recommended services : preventive maintenance.
Frequent oil changes, flushes, trany, diffs and transfer cases oil changes even some brands claims its lifetime.

Just my point of view, based on life experience and Google ))

 

Sorry, but over the years cars have gotten far more reliable and far more capable of lasting hundreds or thousands of miles with minimal maintenance; never before in history has that been more true than now.

 

Another concern is: did you get the oil change you paid for. I trusted a mechanic to do an oil change that I suspect they never did. Before the next oil change I checked the oil level and found it to be lower than I had ever seen and darker than I had ever seen. When I brought it to their attention, they quickly agreed to not charge me for the service. (I suspect they knew they had a problem with an employee.)

Extending the interval increases the impact of a lower quality oil change or one that was never done.

I heard of an older couple that apparently never got the oil changes they paid for with the expected end results.