Wrong. They tried to make the claim so that they can sell more oil and filters and make more money that way, as well as try peddle other services that are either unneeded or needed far less frequently than Jiffy Lube recommends, like transmission flushes and other ripoffs.
I know all that, but that's not what the manual says. It says exactly as I stated.
What, by quoting some Joe Blow at Edmunds? Hardly "Scientific."
They don't even have that right. My car gets to operating temp in no more than 3 miles, even when it's -0 F outside. Beside that, many use their car for long commutes, then jump into them at night or on the weekend go a couple blocks to pick up a gallon of milk or something, never getting the engine warm. Repeatedly.
No surprise that oil companies want to sell more oil.
You just pick an acceptable duration - to you - according to your judgement of what facts are as you see them. BTW, using the above logic, why change at 7,500 mile? Why not 15,000, or 30,000? After all, you're just forking over money to the oil companies. As I said, NOBODY knows the difference 3000 vs 7500 mile oil changes have on the engine in the long run. NOBODY. Even somebody who gets an oil analysis done every change doesn't know the actual effects of those results. Let common sense be your guide if you have no scientific data to back up your inclinations. My mark is 3000 miles, but I'm not religious about it, and sometimes go to 4000. It's not a big deal. The oil gets recycled.
--Vic
Here is a question for you to ponder. How is the "qualified mechanic" going to determine if the little blue haired lady's car needs more frequent oil changes?
Is the Jiffy Lube guy a "qualified mechanic?" How about the "qualified mechanic" whose business is slow? I think she's gonna need more frequent oil changes.
--Vic
How should a qualified mechanic know how often to change oil, other than following the recommended change intervals by the engineers who designed to the car? Mechanics are trained to fix things and do preventive maintenance. They don't have the training in organic chemistry, metallurgy or engineering to make better recommendations than the car makers.
I like the GM system for determining oil change intervals. It is not perfect, but it does at least attempt to modify oil change intervals to compensate for varations in the vehicle usage. I had a Saturn that used it. I never actually waited until the oil change light came on, but with the light providing a stop point, I felt a lot better about extending the oil change interval.
For most of my life I have been a 3000 mile oil change guy. But after seeing how well things went for people I know who change at longer intervals, I decided to go for longer intervals as well. I figure for everything I own,
5000 miles is a good interval.Changing oil too often is not cheap insurance if there is no benefit.
Ed
Most mechanics have working eyeballs. Do you think these engines could use more frequent oil changes?
I only mention it because the car makers love to stick that in the car manual as "severe severe" when it's clear that it's not.
Obviously, they do. However, the vast majority of engines do not build up sludge like that. And, the parts shown are not visible from the outside of the engine. How often should the engine had its oil changed?
What you're making is a straw man argument. You have yet to explain how a mechanic is supposed to know how often to change oil. It is obvious when there is a bunch of sludge in the engine that it should have been more often. But you haven't said how to determine how often.
Now that you mention the GM system.... My 95 Caprice had that in it. We changed the oil, per our fleet policy, every 6000. The oil change light came on almost always about 500 to 1000 miles sooner, IF it came on at all, between resets/oil changes. So based on that I'd say the GM algorithm came pretty close to calling for a 6000 mile interval.
No you are. The question wasn't how often does it need to be changed but has it in the past been changed often enough. That question is usually easy to answer.
Yes. And I'm not going to.
I don't know how that determines a change is due. The manual says it could come on in as little as 2000 miles - or less!, depending on some "conditions" mentioned - speed, temp, etc. My son does my oil changes, and I suppose he could have reset it at some point. I'll have to ask him, but I don't think he ever reset it. The manual is vague, only saying that it should be reset after changing the oil, but not specifying that the light actually on requires the reset. Reset is key in run, engine off, push accelerator to floor 3 times quickly, and light should blink twice and go out. Anyway, the light is on now and has been since we got back from Florida a couple months ago. We changed the oil before we left, and only put about 3000 miles on it before the light came on. First time I ever saw it, but since my wife is its main driver, I'm not sure if was on before.
--Vic
No, the argument with the picture of the sludge-filled engine is part of a straw-man argument.
Correct, because a mechanic is not supposed to know how to determine how often to change the oil independently, but, rather, follow the manufacturer's recommendations.
Jeff
No the picture is extreme example of the point I was making. Anyhow, if the engine is clean the oil has been changed often enough and if it isn't then it hasn't.
Well maybe if he is brain dead.
-jim
Perhaps they could send an oil sample out for analysis, LOL.
What's funny is people that look at their oil and see that it's dark in color and they think that the color is an accurate indicator of whether the oil needs to be replaced. It isn't. A mechanic might ask the owner a series of questions regarding how the vehicle is used, but generally they don't have time for this kind of evaluation on a job that costs $20-30.
Please tell me how a mechanic is supposed to know the organic chemistry, metallurgy and engineering in determining how often the oil needs to be changed.
If very think, chunky oil is coming, obviously, the interval is too long. However, please explain what kind of knowledge base a good mechanic has that let's him/her determine the proper interval better that is better than the one recommended by the car maker.
Jeff
And the mechanic is able to interpret the results of the lab analysis how? The mechanic is able to tell that the lab is a good lab how?
And even if they do, they don't really have the knowledge base to apply the information they get from the owner. Plus, people's guestimates of how they do something (like percent of the miles that are highway miles vs. city miles) is likely to be quite inaccurate. They don't know how other people (e.g., kids, spouses) use the vehicle or drive it, either.
Jeff
One of the largest oil change chains, Jiffy Lube, for instance, is owned by Pennzoil-Quaker State, and as such has an incentive to sell as much of the company?s traditional petroleum-based oil as possible."
This information is only partially correct. Shell Oil owns Pennzoil-Quaker State.
My oil chnage light in my 2009 Dodge Truck comes on around 2500 miles.
That never was the question. Here is the quote
"As a car ages, more frequent changes might be in order, but that's for a qualified mechanic to decide on a case-by-case basis."
Modern oils hold the fine dirt particles that the oil filter do not remove in suspension. But oil can only hold so much dirt. If you change oil often enough the oil changes get rid of the dirt. If you don't change the oil as often them some of the dirt will stay in the engine. If every oil change you leave some dirt in the engine it adds up. This does not require a Ph.D. to comprehend. Examining an old car and determining whether the engines oil needs to be changed more frequently is not the intractable and difficult proposition that you are making it out to be.
I have seen plenty of examples where car manufacturers provide recommendations to mechanics in one form or another to examine the oil and engine to determine if the oil has been changed as often as it should be. Typically this sort of advice comes in service bulletins that are intended to help diagnose engine noises like valve train clatter. More often than not these descriptions do not go into any particular detail of how the mechanic is to make such a analysis. It is assumed that a competent mechanic can tell the difference between a clean engine and one that is not.
-jim
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