RickAnderson
Custom
18-20 vehicles in the last 20 years? That is a new a vehicle every year to barely more than a year. Do you drive 200k miles a year? You not going to see accumulated engine wear on a car a year or two old and if you're driving 200k miles a year, that would have to be mostly highway miles.Warranties schmawrenties.....As much as I drive, they (warranties) are good for 2-3 months. The older I get, the more I wonder about the oil change recommendations....NEVER seen an engine problem with my intervals....regardless of the responses we see here. With my limited experience (18-20 vehicles in last 20 years).
Years ago, everyone would recommend against buying a used Rental car, even though its only a year old and only has 10k miles on it, because it was very likely those 10k miles was abusive. Today, most agree its a very viable option because of the improve quality and longevity of cars, that most will easily go to 100k miles without breakdowns. A year and 10k miles, even if abusive is so little in the life of the modern vehicle its likely a very solid vehicle.
I personally don't put too much into warranty, I do document my preventative maintenance at least till the warranty is up. Remember if you DIY, have receipts showing the parts and materials that you used to prove you complied with intervals and and recommendations for fluid and parts that should be used.
Read up on what degrades the oil, its start-ups and running while not warmed up, idling and operating in extremes, temps and conditions, dust and dirt.
If you drive a 50 mile commute mostly on the highway, in 7500 miles the oil is 15 weeks old and you have done 120 start-ups and warm ups. You can easily go much longer on that oil without it being sheared down or contaminated.
If you drive a 1.5 mile commute in city traffic, in 7500 miles the oil is 9 and half years old, you've done 5000 start-ups and done most of driving while the motor is cold, half your engine run time is idling in stop and go accelerations, some of the harshest usage for an engine and its oil. Yes, the O.M. will have some advice about changing the oil within 6 mo or a year if you don't hit the mileage, but you clearly should change that oil much earlier than the recommended 7500 miles.
So it is very dependent on the conditions and usage as too the interval to change the oil, sure oil and engines have improved greatly, the old 3k mile oil change is really antiquitated, but it is very possible that some conditions and usage would require oil changes much sooner or later than the recommended interval published in the O.M. that is based off the typical usage. If you track it you will find out if you need to do it sooner or later. Oh, if you have one of the those vehicle that tracks it for you, you can go off the tracking the vehicle does of itself.