Oil Changes: How Often?

Do you really need to change your oil every 3 months/3000 miles?

by Tom Torbjornsen

Posted: Feb, 24 2009

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I have been in the auto repair industry since 1972 ... hummmm, a simple calculation of the math illustrates that I have been in car repair for, uh, well, let's not go there. It makes me depressed. You do the math and keep it to yourself. At any rate, enough about my mid life crisis. Let's talk about oil change intervals.

For years the accepted oil change interval (as per the carmakers) has been every 3 months or 3 thousand miles, whichever comes first. Why? Because the oils of yesterday degraded and broke down when left in the crankcase environment for longer than the prescribed interval. The combination of heat, friction, and the oil oxidizing over time resulted in an unholy clothing of the engine's internal parts called sludge. As an automotive machinist for a good part of my career, I can tell you that sludge is an engine killer. Sludge takes a greasy, cake-like oily form and plugs oil return passages and acts like a sponge and soaks up good oil to grow its grotesque form starving the engine of vital lubricants. Once established, engine heat crystallizes it to a hardened rock of ughhhhhh, I have spent many an hour scraping and yes, sometimes chiseling established sludge from the inside of an engine before performing a machining operation on it! As the machinist prepares to perform a machine operation on a cylinder head, crankshaft, engine block or the likes he/she must clean their work meticulously before performing the prescribed operation. If the sludge is not cleaned properly, the result will be a failed engine.

Why this lesson about sludge? Because without clean good quality oil in your car's engine, it will develop sludge and cause premature engine failure.

Now more than ever before, vehicle engines operate at high heat and close tolerances. The reason for this is the Federal Emissions mandates the government has imposed on the carmakers. Vehicles have to emit a smidgeon of the tailpipe emissions they did a decade ago. Carmakers have risen to this occasion by increasing combustion chamber temps with higher compression engines, running leaner fuel systems, adjusting ignition timing for optimum emissions, narrowing cooling system water jackets, and tightening engine oil tolerances. All this makes for hotter running engines that emit less tailpipe emissions. Putting these demands on engines requires a lubricant that can stand up to this harsh environment. Hence, petroleum companies' work hand in hand with carmakers to develop engine lubricants to meet the requirements and demands of a particular powerplant, still delivering the advertised horsepower and torque output that consumers expect. Research and development between carmakers and petroleum companies has resulted in improved engine lubricants that properly lubricate your vehicle's engine as well as keep the inside clean of sludge buildup, AND CAN GO LONGER BETWEEN OIL CHANGES!

A pioneer in extending oil change intervals ...

A few years back, GM introduced a system called the OLM (Oil Life Monitor) system. This system had been in testing since 1984 and actually was put into some Buicks on a test basis. The goal of this system? To extend oil change intervals and attain bragging rights to having a more maintenance-free vehicle. The OLM monitors crankcase temp, moisture, and combustion chamber events (this represents the actual work the engine is doing while in operation). By closely monitoring these elements of engine operation the system can measure the serviceable life of the oil to within 10%. After officially introducing the OLM with virtually no engine failures attributed it the OLM, GM changes their service recommendations to what they called an "Enhanced Maintenance Schedule." With the Enhanced Schedule, the motorist need only follow the dictates of the OLM and have other scheduled services done at prescribed intervals.

Ford Motor Company has followed GM into the extended oil change interval march. In March 2007, Ford announced that they are revising engine oil change intervals to every 7500 miles. The reason? Quoting the article from the Associated Press dated March 22nd, 2007:

"Not only are modern oils better, modern engines are also better. You don't have carburetors metering poorly on winter mornings, tolerances are a lot tighter, and operating temperatures are typically a little hotter, helping to cook off the junk that accumulates in the oil. Ford contends that its customers prefer a set amount of miles between changes. The automaker also cites the environmental benefits that come from less waste oil, monetary savings, as well as extensive tests as positive aspects of the new recommendation."

Yes oil is much better than it used to be, engines are better protected with today's new lubricants but the same old logic still applies to the oil filter: always use a good quality filter when having the engine oil changed. The filter is the storehouse for dirt in the engine and when it doesn't do its job, the engine suffers internally. When dirt and grit are allowed to circulate over, within and on the engine bearing surfaces, cylinder walls, crankshafts, piston rings, camshafts and virtually all metal mating surfaces, they are damaged resulting in wider oil tolerances, lowered oil pressure and ultimately premature engine failure.

While I concur with R&D results over the years with respect to oil change intervals, I am still squeamish about leaving petroleum-based oil in an engine for 7500 miles. I guess I just know too much based on personal experience.

So while yes, I have revised my thinking regarding extending oil change intervals:

Here are my revised oil change recommendations: change regular petroleum based oils every 4-5 thousand miles and synthetic every 5-7 thousand miles.

There, those of you that for years have criticized me as being in the back pocket of petroleum companies for recommending 3 thousand mile oil changes, are you happy now?

'Til next time ... Keep Rollin'

Read these articles for more about oil changes:

- Engine Oil 101

- How to Change Your Oil

- Factors Affecting Oil Change Intervals

- Oil Change Options

- Is Synthetic Oil Better?

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117 comments

lesandmike2598 11:46 AM Jun 23, 2009 Report This!

I have used Castrol Synthetic for years after having to run it in my T-Bird TC. I change my oil in our 01 Escape and 01 Ranger every 10,000 to 12,000 miles. The Escape now has over 250,000 miles and I have never had any engine problem, it doesn't tick or rattle, and still runs like new... Just drove it with the family to the beach 1200 miles and she still doesn't worry me. BTW my Range has 170,000 miles on it... and it is the same... Mike

altebonyf 4:34 PM Jun 16, 2009 Report This!

ive lived by the 3000mi/3mth rule for years with both of my cars (then a 01 ford escort, now a 06 focus) for fear of my engine locking up, yet my aunt seems to change hers once every yr & 1/2 if that often and has never had that happen (93 chevy lumina). i do however notice that once i get close to the oil change date my fuel efficiency seems to go down. is there a connection? -ny'er & daily driver (5mi/day, give or take)

markesham1 7:24 AM Jun 16, 2009 Report This!

AS A SHOP OWNER WE MAKE ABOUT 3 DOLLARS ON EVERY OIL CHANGE WE DONT MAKE ANY MONEY ON L.O.F LUBE OIL FILTER AND OIL DOES BREAK DOWN I THINK YOU CAN GO 5000 MILES BETWEEN LOF BUT WHILE WE HAVE A CAR IN THE AIR WE SET TIRE PRESSURE BETTER FUEL ECON. AND LOOK OVER THE CAR CATCHING THINGS THAT ARE WEARING OUT OR BREAKING THAT SAVE ALOTA MONEY IF A CAR GOES OUT AND BREAKS DOWN U HAVE TO LOOSE TIME FROM WORK WORSE YOUR WIFE GETS STUCK AT NIGHT TOW CHARGE ALOTAOUR WORK COMES FROM INDING BROKEN OR WORN PARTS DURING LOF

joejagent 2:17 PM May 31, 2009 Report This!

I only use Mobil One in all of my cars. I do not drive any of them more than 7500 miles a year (some much less), so I change the oil every year on each. The problem is, the need is based on how you drive and where and that is not easily measured so I believe you should pick something within manufacturer requirements to avoid warranty issues and do ******** really not that expensive (I see deals for $14-20 on a regular basis for petroleum based oil) and the consequences are potentially terrible.

igot35onit 8:25 PM May 23, 2009 Report This!

It really depends on what kind of driving you do. I think evry 5 or 6 thousand miles is fine if you do alot of highway driving. You may need to change it more often if you do alot of stop and go city type driving. Oil is engineered to last longer but I think the 3000 mile thing is just for someone to make money. Oil companies and Dealers make alot of money from the 3000 mile rule.

mrnowrench 11:05 AM May 22, 2009 Report This!

Rolandraele: I'm not trying to pick on you or split hairs here but I couldn't help but notice your comment: "I never changed oil before 7000 miles and never ever had any kind of engine problem because of bad oil." I don't think "bad oil" is the point here. There is no bad oil unless you drain it out of an engine that has gone 25,000 miles without a change. I can gaurantee that if you dis-assembled two similar engines that have been in similar conditions, one has had oil changes every 5000 and the other was stretched to an oil change every 20,000 miles. Lay all the internal engine parts out on two tables or work benches, even a monkey would be able to tell which engine had which maintenance. I personally find it shocking that so many people that have replied to this post think it's ok to let oil changes go that far, regardless of what country you're from. It's cheap/preventive maintenance to properly maintain your vehicle. Nothing is maintenance free ! OK, I've chimed in again,...let the verbal beatings begin !

brian683 9:11 AM May 22, 2009 Report This!

For the record i have been a full time auto tech for the past 6 years and am nearly what gm calls "world class" i personally still believe in oil change intervals of 3000 miles, for one major reason, these days you change oil not because it breaks down, but to get the dirt out, an oil filter can only do soo much, and have you ever seen the oil filter on a gm or foreign car? they are tiny, how much dirt can they possibly hold? however if you own a light duty diesel pickup like i do with an oil capacity of over 10 quarts, then i think 5000 is ok just because there is soo much more oil to suspend that dirt in

bluemaximizer 7:58 PM May 20, 2009 Report This!

I work in a cadillac dealership.the oil life monitor isnt fool proof.you still need to check your oil as per the owners manual,maybe not everytime you fill the gas tank but maybe once a month.yes the synthetic oil has better lubrication quailties?******* also seems to leak easier and burn more.ive seen many cars come in for engine noises and driveability problems,due to low oil level.there are very few cars with oil level sensors.

rolandraele 3:49 AM May 20, 2009 Report This!

Every 3000-7000 miles ? Very funny ! Over here in Europe most modern cars need an oil replacement every 20-40 thousand km (so every 13000-26000 miles or every 2 years, whatever is first). And even on my older cars (driven in the years 1980-2000) I never changed oil before 7000 miles and never ever had any kind of engine problem because of bad oil.

mrnowrench 3:16 PM May 19, 2009 Report This!

To: feliciamoran, yes that is an accurate statement, my brother has an 04 with about the same miles and my friend has an 02 with more miles than yours and the only thing the engine has been opened up for is normal timing belt replacement. Both change their oil between 3000 to 5000 miles.

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117 comments