Oil Change Myth

How often should you changer your oil? Jiffy Lube and Lube Express tell me to come back every 3000 miles or every 3 months, whichever comes first. There's a sticker on my windshield that reminds me of the deadline. Sometimes, I'll even get a discount if I bring my car in before the deadline. They must be really concerned about my car. But it's all a myth. What so magic about 3000 miles? Wouldn't 2000 miles be even better? 1000 miles? Why not just carry around a barrel of oil and put it on a continuous IV drip? From Yahoo! Autos,

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.

While the Jiffy Lube website doesn't explain why they suggest 3,000 miles as the target for changing your motor oil, they do say that it's a "good rule of thumb". The Lube Center, however, does provide some reasoning:

It is a given that we should change our oil on a regular basis, the question is at what interval. Following the manufactures recommendations requires you to know something about your driving conditions in order to select the correct interval for you as shown in acceleration or high-speed driving, extreme hot or cold climates, off road motoring, and carrying or towing heavy loads. The byproducts of combustion in your engine cause your motor oil to break down and no longer protect the internal components the way it should. The rate of this process will vary with each individual motorist. The Lube Center recommends you change your oil every 3,000 miles and receive the best protection your engine can receive.

So 3,000 miles is "the best protection"? I bet 1,000 miles is even better...which would make it "the best". And what does it mean to say the motor oil "breaks down"? Are chemical bonds disassociating? Does the oil change into another substance? You'd think nearly 100 years of motor oil research would have solved this problem.

Well it has. An oil change every 3,000 miles is only a good rule of thumb for companies that would rather profit by perpetuating the myth.

(first seen at Lifehacker)