Case For The 3,000 Mile Oil Change

[ekpolk]

Originally Posted By: JAG

Direct injected gas engines produce significant amounts of soot while port injected gas engines do not. Soot is abrasive so it increases wear and changing oil sooner reduces soot concentration. Direct injected gas engines also increase fuel dilution relative to port-injected ones because some of the liquid-phase gasoline hits the cylinder walls before vaporizing. So yes, for these engines, oil life is reduced. Relative to similar port-injected engines, shorter OCIs and/or better oils are needed if similar protection is the goal.

JAG: I will admit, up front, that I have done little homework on these engines, and don't know a whole lot about them. With this said, the soot thing seems counterintuitive. Why, if DI engines are able to control their mixtures to the n-th degree, including significantly stratified charges, would they be sootier than comparable port injected engines? If anything, I'd think they'd be cleaner???

 

[Colt45ws]

Originally Posted By: ZZman

Originally Posted By: JAG

Direct injected gas engines produce significant amounts of soot while port injected gas engines do not. Soot is abrasive so it increases wear and changing oil sooner reduces soot concentration. Direct injected gas engines also increase fuel dilution relative to port-injected ones because some of the liquid-phase gasoline hits the cylinder walls before vaporizing. So yes, for these engines, oil life is reduced. Relative to similar port-injected engines, shorter OCIs and/or better oils are needed if similar protection is the goal.

I thought these D.I engines vaporized the fuel better and at the exact right time to get better combustion.

Its still throwing some fuel on the cylinder wall and getting past the rings before vaporizing.

 

[ZZman]

http://auto.howstuffworks.com/direct-injection-engine.htm/printable I thought this was interesting.

 

[ZZman]

Something else: http://www.msprotege.com/vbb222/showthread.php?p=4022417

 

[The Critic]

Originally Posted By: Bluestream

Do you have the link that states: "GMInsideNews that technicians believe that extended oil change intervals were partially to blame." I don't see how dirty oil can cause a chain to stretch; Sounds like they're passing the buck due to poor design or poor quality parts...

Here's the explanation. Can't vouch for its accuracy though.

Quote:

I personally wouldnt go over 5k. I have had vehicles in here, specifically Acadia's, with SES lights and codes set for Cam actuators. These are driven by oil pressure, and all of the ones I have seen have not yet had there first oil change. My stepmom's was the first and she had 9500 miles on it, but the OLM still had 20% left. We changed the oil, cleared the codes and she now has 20k and we have done them every 4-5k since then without any problems. The thought is the oil had broken down and couldnt provided proper oil pressure to the cam actuators. Weird, but a good example of how GM's recommendations can vary based on driving conditions, and arent concrete.

http://www.gminsidenews.com/forums/f53/oil-changes-60436/#post1308831

 

[BobFout]

Originally Posted By: JAG

Direct injected gas engines produce significant amounts of soot while port injected gas engines do not. Soot is abrasive so it increases wear and changing oil sooner reduces soot concentration. Direct injected gas engines also increase fuel dilution relative to port-injected ones because some of the liquid-phase gasoline hits the cylinder walls before vaporizing. So yes, for these engines, oil life is reduced. Relative to similar port-injected engines, shorter OCIs and/or better oils are needed if similar protection is the goal.

These are not issues for diesel oils in DI diesels, sounds like you're right, it's time for better PCMOs.

 

[pavelow]

See, all of us 3000 mile OCI'ers have known we were doing something right all along. Oil is always cheaper than a new engine.

 

[Steve S]

Gm 3.6 lack quality.

 

[buster]

The 3,000 mile myth needs to die, and I believe it is. Playing it safe, stick with what the owner's manual says. DI engines are not the norm yet, and I suspect something isn't quite as good as it should be for fuel dilution to be such a common problem within those engine types. The numbers speak for themselves though, oil change intervals have been extended, and engine durability has gone up as well.

 

[daman]

Originally Posted By: buster

The 3,000 mile myth needs to die,

I agree but i don't see it dieing yet,that's all you hear and read about is 3k,3k,these oil company's want the revenue with oil sales so it's here to stay probably.

 

[buster]

Yeah it hasn't died yet because of the quick lube cult.

 

[The Critic]

Originally Posted By: buster

Yeah it hasn't died yet because of the quick lube cult.

Not sure if it needs to die, to be honest. Considering that many cars are low on air pressure, out of washer fluid and are in need of some work after a few months, a 3mo/3k interval actually makes sense as it allows the car to get a quick inspection. Until they make cars that don't burn oil, tires that don't lose any air and 10 gallon washer fluid reservoirs, then every 3 mo/3k isn't a bad idea.

 

[buster]

Eh 3/3 is a myth and just bad economically. It's definitely safe to follow. Wasting a lot of oil though. Years ago, it was probably a good thing to follow unless you were using Amsoil or Mobil 1. When people buy a car, it is their responsibility to follow what it says in the owners manual. Quick Lubes just profit off volume. Plus, most OEM's are at least calling for 5k mile drain intervals on average. The new Mustang will go 10k on MC. The industry is slowly evolving. If you car burns oil, adding oil will help you extend drains. It's the owner's responsibility to check the oil level. If you can't do that, you shouldn't own a car.

 

[Gary Allan]

Originally Posted By: The Critic

Originally Posted By: buster

Yeah it hasn't died yet because of the quick lube cult.

Not sure if it needs to die, to be honest. Considering that many cars are low on air pressure, out of washer fluid and are in need of some work after a few months, a 3mo/3k interval actually makes sense as it allows the car to get a quick inspection. Until they make cars that don't burn oil, tires that don't lose any air and 10 gallon washer fluid reservoirs, then every 3 mo/3k isn't a bad idea.

I sorta agree. I often find myself without words (few enough) to tell someone ignorant of machines how to care for their car. They may be otherwise quite intelligent, just not into machines. We tend to do more with our retail savings than someone going to a quicklube. In that sense, I don't think that we save any money either.

 

[ottotheclown]

Ok, Ok, we must notify Chrysler, Ford, Nissan etc that suggest 3,000 oci with severe service that they are wrong. We have discovered this is a waste of oil and a myth. It is amazing they the engineeing dept. still go by what the quick lubes made do for all these years. Not to mention uncle Winifred, in Maine who has 345,000 on his AMC Gremlin, doing 12,000 oci with Mobil 1. I will sleep well tonite..

 

[addyguy]

Yeah, this is a bit contradictory. Most of us say 3k is dead, is a waste of oil, oils can do at least 5k...etc... Then we say 'follow your owners manuals'....most OM's say 3k for the typw of driving most of us do (severe). From UOA's, I know I can get 7-8k out of oil before it's exhausted. But my OM says I should be doing 3k on the nose. So, sometimes I think I should go back to 3k, to follow 'common sense'....or is it????

 

[Mystic]

I can think of a lot of reasons why somebody might want to do 3000/3 month oil changes. Here are a few: In my owner's manual it says that unless somebody is driving in ideal conditions (read the fine print-almost nobody drives like that) 3000/3 month oil changes are required. In the case of sludge monster engines (and there have been a few) after you get the engine cleaned up you would want to do frequent oil changes. Somebody driving in severe dust conditions, or some other severe conditions, might require frequent oil changes. If you are trying to clean up a dirty engine, it might make sense to do fairly frequent oil changes with one of these new motor oils that are supposed to clean an engine up. You could go back to longer oil changes after you have finished cleaning up the engine. I personally feel that conventional motor oils are really best for about 3000/3 month oil changes. When you can walk into Wal-Mart and buy a 5 quart container of oil for 12 bucks or even less plus get an oil filter an oil change is pretty dang cheap. At those prices I don't feel like an endurance run to see if the conventional oil can last 15,000 miles. If somebody has a problem like coolant getting into the oil (you really need to fix the problem of course) you need to change the oil frequently. And if somebody wants to do 3000/3 month oil changes, it is THEIR money.

 

[The Critic]

And over the years, I've also wondered another thing. Gaskets. Intake gaskets and headgaskets that seal off coolant. They cannot possibly be 100% effective, maybe 99.99999%, but they have to let something through. Over an extended drain, wouldn't small amounts of coolant end up in the crankcase? Also, a number of techs have told me from first-hand experience that oil tends to stay fairly clean in cars from 0 to about 75k. After that, oil tends to get dirty far more quickly as the older engines have more blowby. So, wouldn't it make sense to follow a shorter interval especially once the engine gets older?

 

[SilverC6]

I like 3000 mi. for my son's RX8 because fuel dilution is a factor for the rotary engine. The other vehicles in my fleet will get changed annually or somewhere between 3000 and 5000 mi.

 

[ekpolk]

Originally Posted By: The Critic

And over the years, I've also wondered another thing. Gaskets. Intake gaskets and headgaskets that seal off coolant. They cannot possibly be 100% effective, maybe 99.99999%, but they have to let something through. Over an extended drain, wouldn't small amounts of coolant end up in the crankcase? Also, a number of techs have told me from first-hand experience that oil tends to stay fairly clean in cars from 0 to about 75k. After that, oil tends to get dirty far more quickly as the older engines have more blowby. So, wouldn't it make sense to follow a shorter interval especially once the engine gets older?

Well Mike, this harkens to an issue we see here on a fairly repeated basis: whether one's oil change decisions and plans should be made and established on a preemptive basis, or whether to be guided by UOA (or perhaps other methods such as blot cards, etc.). Assuming one chooses anything except the shortest of OCI, then at some point in an engine's life, just wear over time will probably cause a noteworthy increase in the amount of "stuff" ending up in the oil. Whether this merits a change to very short OCI like 3k? Anyone's guess (or question for more scientific analysis).