Personal opinion about oil change intervals.

Something that manufacturers have begun to keep a close watch on is the cost of ownership of a car, not just the initial purchase price. When the typical publication reviews vehicles they often use the manufacturers published specifications to project the cost of ownership over a year. On extended long term road tests, as some monthly magazines do the oil change interval and maintaince can start to have a noticeable effect on the price of ownership.

If we take into account the manufacturers specs of 7500 miles for an oil change, fifty thousand, seventy five thousand or even one hundred thousand miles for transmission fluid change, similar for spark plugs it can have a significant reduction in two years over the typical 3000 mile oil change, 20k miles on the trans, and 40k on the plugs.

Additionally, the manufacturer doesn't expect the original owner to keep the car for more than 75k miles, so why write their specs in such a way to project a higher cost of ownership? Let the next owner without a warrantee worry abut the sludge in the valve covers, and a ring and bearing job.

As for "warming" up the engine, almost every car sold in the US since 1995 has recommend to warm up the engine no more than 10 seconds, no matter what the weather. This has little, or nothing to do with the oil or the life of the engine, but the speed at which the catalytic converter can heat up. Extended warm up or light driving only prolongs the time before the cat can "light off". Short warms ups are better for emissions, but harder on your engine.

I've had three cars in the past that had over 200,000 miles on them and never had any internal engine work done, with regular 3000 mile oil changes and proper maintaince. All three went on to other owner that got many more miles out of them.

So, in my opinion, if your planning on keeping the car a long time, use short oil changes, if your gonna trade it after a few years, save your money, and let the next owner worry about it.

Two questions-

1)When did the interval for oil changes start lengthening? E.g. how new does a car need to be to go 5000 miles on an oil change?

2)If the oil life monitor is affected by how hard you drive the vehicle, could a rental company use these as a method of monitoring vehicle abuse?

I drive my 10 year old car less than 1000 miles in 3 months. When should I get the oil changed? I have NEVER taken it in and been told it doesn't need an oil change.

Suzanne, while there are different recommendations on how long you should go between oil changes, changing your oil is regular maintenance and is something that needs to be done.

You probably shouldn't take any more advice from the person who told you "it doesn't need an oil change," or at least not any advice about car maintenance.

For a car 10 years old, 3 months or 3,000 miles -- whichever comes first -- is a good oil change interval to follow.

I plan to trade my car in as soon as I reach the end of the 36,000 mile warranty so I put synthetic oil in at the first change and I'll never change it again!

Still changing oil at 3000 miles is to deny the advances that have occurred with that product. My father use to change the oil every 3000 miles and he was born at the turn of the century. Wake up the cars and the oil are not the same.

Iam the second owner of a GM Truck with 13,000 miles and it is still under warranty. I prefer to change my own oil and filter. Can I continue to do that, or do I have to take it to a GM or quick lube to maintain the warranty.

Tom, that's a good question, we're going to look into it for you to get you a full answer.

Tom, it is illegal for a dealership/car company to require any services to be done by their techinicians in order to keep up the warranty. So have at it and get dirty!

I change my oil at 5000 miles regardless of time since last oil change. I also check spark plugs and use fuel injector cleaner each 5000 miles. This is all the preventive maintainence my car seems to need to purr like a kitten and still get 38 MPG. I drive a 19 year old Nissan Sentra that just turned 300,000 miles on the original motor.

Wow...19 year old car??? Half of the population doesn't even keep a spouse that long!

I recently purchased a 2008 Xterra and the manufacturer recommends oil changes at 6000 Kilometers ( 3744 miles ) or 3 months. I likely will never put that mileage on in 3 months so why would it not be better to go with MILEAGE intervals ONLY rather than confuse the issue with CALENDER intervals.

John, see this response:

http://ask.cars.com/2007/11/oil-change-reco.html

Basically, mileage isn't the only determining factor of engine oil's lubrication life. Your driving habits and environment can influence the life expectancy of the oil as well as the mileage.

At what percentage of oil life should I change my oil?

I have driven a Suzuki Gran Vitara, 2000 cc automatic European version, now for about 11.500Km ( 7.500 Miles? ) and tomorrow will be the second year of its life, April 1 2008. I have not yet changed the oil as my mechanic said I should wait until I reach the 15.000 Km suggested by the manifacturer. The car is doing just fine and drives like new and the fuel consumption is slightly better than it was at the very beginning. Consider that where I live the temperature is in the 20 centigrade or above ( 70's ) all year around. Bula from Fiji

On the oil change debate, some facts (as I understand them) and one objective data point.

1. Oil change intervals increased in part because manufacturers are mandated to estimate fuel & oil consumption for the first 100,000 miles. Increasing the interval decreases oil consumption.

2. Oil doesn't (usually) wear out. it gets contaminated with combustion byproducts and some of it's additives lose their properties. Todays engines with hypereutetic pistons and precisely monitored fuel/air ratios minimize the byproduct contamination, so oil does last a bit longer.

3. However, frequent oil changes do make a well cared for and un-abused engine last longer. (Here's the data point.) I have a '93 Chevy C-1500 pick up with the 5.7L engine thyat has ~305,000 miles on the original engine and it runs fine, passes emissions, and doesn't burn oil. I've changed the oil 101 times. I'm on my third tranny and second rear end, but the engine runs fine, and it is a well used (but not abused) work truck. I routinely get over 200,000 miles on my wife's cars (last three were Caddy's) and again, change the oil & filter every 3,000 mile.

I change the oil every 3,000 miles on every new car I buy for as long as I own the car. Works for me and I recommend it.

I'm curious about the earlier comment on the legality of a dealership requiring service to be done by the dealer in order to maintain a warranty. Our dealer requires that we have oil changes done there in order to validate a warranty on the drive train. In this case, however, the warranty was provided by the dealership and was advertised as an incentive to buy the car. I wanted to buy the car without it but they kept including it in the deal. Could it be that a different law applies because it's not the factory warranty? Or is the earlier statement (about it being illegal) false?

I have been searching the internet all morning trying to find an answer on what mileage to change when using full synthetic oil. I have read several different stories on what mileage to change your oil if you are using full synthetic oil. Does anybody know what mileage I should change the oil in a 2007 Dodge Durango 4.7liter V-8 using Mobil 1 full synthetic?

Matthew, I don't know about Mobil 1 but in the case of
AMSOIL synthetic oil it can be changed YEARLY or 25,000 miles. Most people don't drive 25K/Yr.
I have been using it for 14 yrs now in the same car
a '71 Datsun 1200 and recently turned 600,000 miles.
I put in my 3rd engine 2 yrs ago but the first two engines got aprox 250,000 miles each. 4 Cyl(1190cc)
I like the little car so much I just can't part with it. Baja

I own a '93 Toyota Corolla with under 1000,000 on it. I have my oil changed every 3 months. My mechanic told me to use Shell gas to prolong the life of my car because Shell has better additives to keep the engine clean. Is this true?

I have a 2003 Ford Focus SE (2.3L), with 67,000 on it...It drives like a sports car, is a fun car to drive and gets very good mileage (25-27 city and between 35-37 mpg hwy.)
I have been using Mobil 1 (extended drain), which Mobil claims will go to 15,000. I decided to not push it...and change the oil out at about 12,500...but I changed the filter out at about 6500.
I will be changing to Valvoline Full Synthetic (5W20) when I'm ready to drain the Mobil 1.
My plan with Valvoline is to go approximately 7,500 between changes. I contacted Vavoline and they responded by saying that this should work just fine.
NOTE: I noticed that this thread does not mention the value of getting a 'good' filter. After much research, I decided to only use the Purolator PureOne (not the regular Purolators) OR the Mobil 1 filter. Both rank high in testing. The PureOne costs about half of what the Mobile 1 costs. I'm sure ther are other 'good' filters out there, (Wix, Napa Gold, Bosch) but stay away from Fram.
ONE ADDITIONAL TIP: I purchased a special (very strong magnet), made especially for autos, and attached it to the end of my filter. This will pick up microscopic metal that passes thru the filter, which will wear your engin out faster. I also have a magnet placed right near the oil pan drain hole.
These magnets can be used over and over each time you change the oil. Contact me for the website to purchase these magnets.

I have a car that sits in the garage for 99% of the year and gets less than 500 miles in a year. The car has an 8 litre sump and the oil is as new after 2 years. Why would the oil need to be changed after 3 months if the car has not been driven during those 3 months? Does the oil break down while sitting in the sump?
I only drive the car a couple of times a year and with what I read here it would mean I would have to change the oil every time I drive the car?? This does not make sense.

Just to clarify a bit... it is not illegal for a company to require service to be done at a certain place to keep a warranty - if they provide the service for free. This has been an issue on some higher end cars like BMW that have provided service for free for the first x miles. If it is not free, then no the service (or oil used for that matter) can be performed elsewhere.

Motor oils in 2008 are far superior to the oils of just ten years ago. If the oil and filter is changed every 5,000 miles, an engine should provide 300,000 to 500,000 miles of reliable service.

Although owner's manuals suggest new cars need little beyond oil changes, I prefer to change the radiator fluid and transmissions fluid, and PCV valve every 30,000 miles. The dealer charges me a total of $150 to do all of these services.

As a result, my current car, with 270,000 miles, has never needed an engine repair or transmission repair. It runs like new, and I expect it will be running like new when I get to 500,000 miles.

Paul, you asked whether a car that sits in the garage should have its oil changed. Mobil says that even its 15,000 mile Mobil I oil should be changed once a year, even if the car has not been driven.

Car engines and exhause systems can corrode from condensation and moisture build-up. It would do your car a lot of good to take it out on the freeway once a week for a 30 mile run at 60 mph. The engine would reach full operating temperature, and all of the moisture in the engine and exhaust system would get burned off.

Oddly, a car that gets on the highway 30 minutes a week could last for decades...a car stored in the garage that NEVER gets on the road could suffer serious engine problems.

Elizabeth, you asked if you should use Shell gasoline. Many car makers, including BMW and Toyota want their owners to use "Top Tier" certified gasoline. Shell sells "Top Tier" certified gasoline, and their premium gasoline has 300% more additives than the "Top Tier" program requires.

You can go to the "Top Tier" website for a list of the companies that sell "Top Tier" certified gasoline. Any of those brands will work well in any modern engine, and will help reduce the engine "gunk" left behind when you use non-certified gasoline.

I know all kinds of guys that change oil every 3k mi. but use a junk filter and never change tranny fluid, go figure!