So. Let's talk oil...

[Jay2TheRescue]

The 20,000 - 30,000 mile interval might be fine for a new vehicle with a full synthetic oil and a quality filter. Although I use both a full synthetic and quality filters, I am not comfortable with that kind of interval on a vehicle as old as or with the mileage my truck has. If I did a 20,000 mile interval with the amount of mileage I currently put on the vehicle, it would probably be about 4-6 years to rack up 20,000 miles. At the 5,000 mile interval I change the oil at 12-18 months usually.

[trollbait]

My wife's 2001 Sable only has 60k miles on it. I don't track miles for oil changes for it, and just do it once a year. Usually I just use Supertech, but might splurge for Motorcraft or Valvoline high mileage.

If I were to use a synthetic in it, I would just change the oil every other year.

[Jcp385]

AmsOil and a recommended filter would be the only way I would ever feel comfortable going that kind of interval on an oil change...

[trollbait]

A synthetic oil should be resistant oxidative breakdown over that time period. The biggest concern will be water in the oil. It builds up over time from condensation. If the car is regularly taken on long drives where the oil gets hot enough to boil the water off, then it shouldn't be an issue though.

Our Sable sees mostly short trips. So I do the once a year change with a cheap regular oil. A synthetic would be overkill, and a waste of money in its case.

[DPTyphoon]

I have several vehicles / engines that with their limited annual use (less than a few hundred miles a year) only receive an oil change every 5 years or so. Some of these engines (the boats) and vehicles have been in "the fleet" for 30 years or more, so I have meaningful empirical evidence that 5 year changes are fine for me.

To establish a reasonable interval for the 7.3 Powerstroke Diesel in my F250, I kept extending the change intervals, and having an analysis of TBN performed every change. (TBN is the quality of oil that "wears out", requiring a change to prevent engine damage from acid formation). I have decided on 12,500 mile or two-years as the interval for it. It uses 16qts of oil, and a $20 filter, so too-frequent changes cost real money.

I've owned and operated engines and vehicles for over 40 years. I have accumulated over 1.2 million miles on my personal vehicles. I have NEVER experienced an oil-related engine failure. And I would know, as I maintain and rebuild my own engines, transmissions, etc.

In the 70's oil formulations wasn't as good as now days. Engines ran dirtier, and fuel contained more acid-forming compounds than it does today. The 3,000 mile change interval made sense then. But today's oils are better, and engines run cleaner. I feel 7,500 mile intervals are fine for my daily-drivers. 12,500 for the Diesel that holds 16 quarts of oil, and 5 years for the garage-queens.

[Jcp385]

Eh I got the oil for a song. I'm gonna just use it

[Jay2TheRescue]

The only vehicle I don't use synthetic in is the 2000 GMC 1 ton van. We usually drive it about 300 miles a year. We just have the $20 oil change done at the Shell station once a year when the inspection is due.

[Draigflag]

Originally Posted by Jay2TheRescue

The only vehicle I don't use synthetic in is the 2000 GMC 1 ton van. We usually drive it about 300 miles a year. We just have the $20 oil change done at the Shell station once a year when the inspection is due.

You change the oil after 300 miles?! This is insane!

[Matt715]

Originally Posted by Draigflag

You change the oil after 300 miles?! This is insane!

It's not insane if he short trips it for the whole 300 miles due to condensation and fuel contamination.

[Draigflag]

Originally Posted by Matt715

It's not insane if he short trips it for the whole 300 miles due to condensation and fuel contamination.

To me it's insane, oil is a precious liquid and should not be wasted. It should be conserved when ever and where ever possible. Even in the slight chance oil related problems were to occur, it would take 50 to 100 years or more doing just 300 per annum. Like the chap above says, 5 year intervals are fine for low mileage vehicles.