The 3,000 Mile Oil Change Myth

Yahoo Autos ^ | June 17, 2008 | Bill Siuru

[Disturbin]

According to a recent study by the California Integrated Waste Management Board, 73 percent of California drivers change their oil more frequently than required. This same scenario no doubt repeats itself across the country. Besides wasting money, this translates into unnecessary consumption of $100-a-barrel oil, much of it imported.

Using 2005 data, the Board estimates that Californians alone generate about 153.5 million gallons of waste oil annually, of which only about 60 percent is recycled. Used motor oil poses the greatest environmental risk of all automotive fluids because it is insoluble, persistent, and contains heavy metal and toxic chemicals. One gallon of used oil can foul the taste of one million gallons of water.

It’s been a misconception for years that engine oil should be changed every 3000 miles, even though most auto manufacturers now recommend oil changes at 5,000, 7,000, or even 10,000 mile intervals under normal driving conditions.

Greatly improved oils, including synthetic oils, coupled with better engines mean longer spans between oil changes without harming an engine. The 3000 mile interval is a carryover from days when engines used single-grade, non-detergent oils.

For several years, automakers like General Motors, BMW, and Mercedes-Benz have installed computerized systems that alert drivers via an instrument panel light when it’s time to change oil. As an example, the General Motor Oil Life System (GMOLS) analyzes the engine temperature, rpms, vehicle speeds, and other driving conditions to calculate the rate of engine oil degradation. Then, software calculates when the oil needs to be changed. Other systems work similarly.

Because of the many external conditions and parameters that have to be taken into account, calculating the precise maximum service interval using mathematical models alone is difficult. Now, Daimler AG has developed a more direct and precise way to monitor oil quality directly on board a vehicle.

Daimler uses a special sensor integrated into the oil circuit to monitor engine oil directly. Oil doesn’t wear out, but rather dirt and impurities cause oil to lose its ability to lubricate properly, dictating the need for a change. Daimler uses the oil’s “permittivity,” that is, the ability to polarize in response to the electric field. If the engine oil is contaminated by water or soot particles, it polarizes to a greater extent and its permittivity increases.

To evaluate the quality of the oil, permittivity is measured by applying an AC potential between the interior and exterior pipes of an oil-filled sensor to determine how well the oil transmits the applied electric field.

Because not all impurities can be measured with sufficient precision via the electric field method, Daimler also measures the oil’s viscosity to detect any fuel that may have seeped into the oil. Daimler researchers measure viscosity while the vehicle is in motion by observing the oil's side-to-side motion in the oil sump. The slower the oil moves, the higher its viscosity. This movement is registered by a sensor and the viscosity is calculated on this basis.

A single sensor, along with the information already monitored by on-board computers, is sufficient to determine the various parameters of the engine oil. Daimler will likely use the technology first on its commercial vehicles. Here, large oil reservoirs mean larger quantities of oil can be saved. Plus, a predicted 25 percent increase between service intervals and reduced downtime will be of interest to fleets, and thus justify the added cost of installation.

[kbennkc]

Thanks .

[Disturbin]

That’s true, you do have to do a quick oil change after a rebuild to get shavings and remnants of assembly lubes, etc.

[PSYCHO-FREEP]

Synthetic oils will not break down like conventional oils under engine related heat.

The molecules are made to be stable which is why it is called synthesized in the first place.

The only thing that will lubricate in space is synthetic oil. Also, Helicopter/Turbine bearings reach 500 to 700 degrees in the Hot-End and the ONLY thing that will lubricate them is Synthetic.

[Ditto]

I've seen many a Dodge Dart corroded to junk with a perfectly serviceable slant six under what was left of the hood.

I had one -- a '73. You could watch it rust before your eyes. Patching to body wasn't too bad. I even got pretty good at it. But when the frame rotted, that was the end. And it was a perfectly good engine and transmission that went to the junk yard along with the rust.

[Kirkwood]

In WWII, maintenance on vehicles was usually just topping off the oil and not changing it. Some engines lasted for years without an oil change. Still, probably not a good thing, but oil was harder to come by. If an engine eventually died, you just replaced the entire vehicle.

[Malsua]

He said the best procedure you can do to protect your engine on a new car is to change your oil at the 50-100 mile mark. By then the metal shavings/any possible dirt from manufacturing will be in the oil and then is the time to get rid of it. 5-6k changes after that are fine.

This isn't the case on certain new cars. I used to build race engines and I'd change the oil after about 2 miles (8 passes).

Hondas for example, add extra moly to the initial oil fill to help the break-in period. The oil should NOT be changed before 4000 miles on a new Honda or Acura.

[Nonstatist]

Yea, I’m lining up to buy a used car from you . .

Excellent! I've got the perfect car for you! It's a 1989 Yugo with only 26,000 miles on it and you can have it for 800 bucks! A great deal!

[PSYCHO-FREEP]

All modern engines are not built like they used to. It is not necessary to change “break-in” oil any more. Engines are built separately, run-in and completely ready for the road before they are even sent to the assembly plant.

All new engines are broken in at the time of manufacture, completely flushed, and highly purged from manufacturing debris, as well as filtered carefully during the break-in process.

Rebuilt engines from private shops are the only thing that apply to that old principle.

[CodeToad]

“One gallon of used oil can foul the taste of one million gallons of water,”

Typical liberal tripe used as propaganda. Saying this out of the blue suggests people are dumping oil into water supplies when that is far from the truth.

[Pikachu_Dad]

Liability for THEM.

[kidd]

I never change oil until 5K miles. If your driving is mostly highway driving, and you keep your speed under 70, you can probably go to 7K miles, even with non-synthetic oil. Our Honda CRV has an oil sensor. We typically go 8K miles before needing an oil change.

Actually, the article you posted has little to do with being “green” other than used motor oil is a water pollutant (which it is). There is no mention of global warming or other such tripe. The article you posted has more to do with saving money.

[Kirkwood]

“My Dad use to sometimes pour the used oil onto our dusty driveway to keep the dust down. It worked, but can you imagine doing that today?”

The county where I grew up used to oil down dirt roads with sprayers attached to backs of trucks. Most back roads back then were gravel, but we still had a few well-traveled dirt roads.

[boogerbear]

I got over 200,000 miles on my last car before I got sick of looking at it, usually with one “big” ($300 ish) repair a year. I think I’ll keep changing my oil “too” often.

[devane617]

I have always heard that if a tranny is not maintained on a regular basis, then it creates more problems when fluid is changed. If it necessary, be sure it is thoroughly flushed, and not simply changed. Do a google and you will see tons of info on this subject. Best to change the fluid and filter at least every thirty k during the life of the car...we are talking auto tranny...

[ejonesie22]

Just add enough to keep her topped up. As far as the filter, depends on the miles. if you are near or over 100K, I would not bother, or at least reuse some of the fluid, perhaps adding a quart of new at most.

[Old Mountain man]

One thing I learned in aircraft school was that keeping the oil filter changed was almost as effective as changing the oil and filter.

[Blood of Tyrants]

Corrosion? Not in the most of the ‘60s cars outside the rust belt. Because roads were MUCH worse than today(unpaved country roads were more common than paved roads) the car was rattled to death and abrasive road dust exacerbated the problem. Everything squeaked and rattled. Worn door hinges caused the doors to sag which misaligned the door and allowed dust in the car. At 60k, every oil seal on the car started to leak, and at 80k, it usually started to burn oil. At 100k the car was classified as a junker and might hobble along leaking oil and smoking like a freight train for a few more years.

[Kirkwood]

“All modern engines are not built like they used to. It is not necessary to change “break-in” oil any more. “

I have to say you are all wet. My last new Lexus required a 1,000 mile fluid change and the dealer even paid for it. It makes sense to do this and for manufacturers and dealers to require this to limit their liability under warranty. Better to change the fluids than to take a chance of having to rebuild an engine and replace bearings due to some stray chips.

[Disturbin]

I was referring to rebuilds done by us.

I just assembled an engine, broke it in, then changed the oil.

[McGruff]

I have been using Mobil1 synthetic oil for years and routinely go 15k miles between oil changes. But I do alot of highway commuting type driving. If you tow something or just drive a few miles and stop I'd go with the 3k recommendation and skip the synthetic oil. The owner's manual states it pretty clear. Dealer's make a lot of money from oil changes.