Automakers Lengthen Oil Change Intervals
in [Cars]
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From: SMS on 27 Mar 2007 20:29 jim wrote: > Whether your habits are idiotic or not depends on how long you expect to > keep the car. The average new car buyer sells or trades in his car long > before the extended oil changes make any difference that affects the > price he gets for the car. So for most new car buyers changing the oil > every 3000k is a waste of time and money as the only one who will > benefit is someone else who owns the car much later in its life. Not even that person will benefit. The key is to find the interval where changing it more frequently will have no effect on engine life. Changing it at 1000 miles, 3000 miles, or 5000 miles will result in the same engine longevity. The oil is able to suspend sufficient particulates for these intervals, and does not lose either it's lubrication properties or its detergent properties. There is absolutely nothing to support more frequent oil changes than 5000 miles. The exception is if the car is used in truly severe service, i.e. 100% short trips where the engine never heats up to operating temperature long enough for water in the oil to be vaporized. There are also a very few vehicles where more frequent oil changes help prevent other service issues, such as the old Saturn timing chain problem. Ask the 3000 mile oil change advocates why they don't change their oil at 2000 miles, or 1000 miles, or 500 miles. 3000 miles came out of thin air, with no scientific evidence to back it up, so why not go to even a shorter interval, after all it's "cheap insurance," and everyone knows that you should buy as much cheap insurance as possible. OTOH, there have been extensive tests of engine wear at various oil change intervals, and none have ever shown more wear with a 3000 mile oil change than with a 5000 mile oil change.
From: John Henderson on 27 Mar 2007 20:33 jim wrote: > Yes you are absolutely correct. In the 60's the 3000 mile oil > change interval ensured that the vehicle would make it through > the warranty period. Today on most vehicles the benefits of > changing oil every 3000 miles won't show up until 200,000 or > 300,000 miles. So the question really boils down to -> Are you > planning on keeping the vehicle that long? Well you can take from someone who regularly keeps their vehicles for 10 or 20 years that 6000 mile oil changes keep engines in very good condition past the mileages you mention. If I was usually driving only short distances, I'd change it sooner. The last vehicles in which I changed oil at 3000 mile intervals were my air-cooled VWs (with no oil filter). John
From: SMS on 27 Mar 2007 20:37 Scott Dorsey wrote: > It would strike me also that car manufacturers would want you to change your > oil less often too, because they want to sell you a new car as soon as > possible. It's not in their best interest that your engine last forever. Nice theory, but no automaker would push a maintenance schedule that would cause their vehicles to have premature engine failures. First of all, the owner would be highly unlikely to buy the same make of car if he or she experienced a premature engine failure. Second, manufacturers don't want to gain a reputation for poor long term dependability. Third, car dealers make a lot of money from performing scheduled maintenance. How many people do you know that only buy a new car when the engine in their current vehicle is destroyed by infrequent enough oil changes? As to the EPA, I don't know how much they care about recreational oil changes (<5000 mile oil changes). The used oil is recycled, and used in truck fleets, it isn't poured into the ocean or into the sewer (well some backyard mechanics might do this). The sad thing is that so many people have been brainwashed by companies like Jiffy Lube.
From: SMS on 27 Mar 2007 20:43 Willy wrote: > We've been well marketed by the oil change chains and auto dealers to change > MUCH more often than is necessary or recommended. I don't think you can blame the car dealers, at least not any of the one's I've been to in the past 25 years or so. None of them are still pushing the 3000 mile myth. The oil change industry, such as Jiffy Lube, is another story. Their whole business model depends on the 3000 mile myth.
From: SMS on 27 Mar 2007 20:51
John Henderson wrote: > jim wrote: > >> Yes you are absolutely correct. In the 60's the 3000 mile oil >> change interval ensured that the vehicle would make it through >> the warranty period. Today on most vehicles the benefits of >> changing oil every 3000 miles won't show up until 200,000 or >> 300,000 miles. So the question really boils down to -> Are you >> planning on keeping the vehicle that long? > > Well you can take from someone who regularly keeps their > vehicles for 10 or 20 years that 6000 mile oil changes keep > engines in very good condition past the mileages you mention. > If I was usually driving only short distances, I'd change it > sooner. > > The last vehicles in which I changed oil at 3000 mile intervals > were my air-cooled VWs (with no oil filter). The 3000 mile interval was back in the days before multi-weight detergent motor oil. These older oils had too high of a viscosity when cold, and could not suspend particulates. Can you even still buy plain SAE-30 oil any more? It would be a bad idea to use it in a vehicle, but maybe some power equipment such as lawnmowers still need it. I've had cars with well over 200,000 miles on them with 5000 mile oil changes. When I sold them the engine was still in good shape with compression ratios well within spec, and the new owners drove them for about another 100,000 miles. Even then, the engine was still fine, but other parts of the car were beginning to wear out, and I don't know how long after the second owner sold them they continued to be used. |