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Car Forum / Driving, Maintenance, Tuning / Maintenance and Repair / October 2005Synthetic Oil Changes
My independent GM mechanic, whom I trust, has recommended to me that I use synthetic oil in my recently-purchased 2004 Impala, and use this mx schedule: change filter (AC Delco only) every 3000 miles, change oil every third filter. Sounds reasonable. Do any of the experts on this newsgroup have any opinions on this? Thanks, Jim Thomas >My independent GM mechanic, whom I trust, has recommended to me that I >use synthetic oil in my recently-purchased 2004 Impala, and use this mx [quoted text clipped - 5 lines] > >Jim Thomas Depends on the kind of driving you do. Changing the filter only removes particulates, not acids, and other crap from condensation in the oil sump. If you're on the highway all the time OK. For driving around town, dump the dino oil every 90 days and slap a new filter on at the same time, regardless of mileage. Lg thanks!! any other tips? > >My independent GM mechanic, whom I trust, has recommended to me that I > >use synthetic oil in my recently-purchased 2004 Impala, and use this mx [quoted text clipped - 15 lines] > > Lg >thanks!! > >any other tips? Tips depend on skill level of car owner/operator ;-\ One that is a Safe Bet: clean your headlights, turn signals, stop lights when you fill up at the gas station, using their window cleaner and sponge. Lg >> >My independent GM mechanic, whom I trust, has recommended to me that I >> >use synthetic oil in my recently-purchased 2004 Impala, and use this mx [quoted text clipped - 15 lines] >> >> Lg Just Googled "compare oil filter specs" and found some interesting stuff. with GM's OLS expectations are 4,000 mi. to 7,000 mi. With highway driving you could do as much as 12,000 miles. GM senior project engineer Robert Stockwell has been studying analyzed oil samples from vehicles with OLS. This GM spokesperson has revealed tests where done w/ regular petroleum based oil, that showed oil change intervals of 10,000 mi. , 14,000 m. and even one did 16,000 miles. With synthetic lube and superior filters you could do even more. For curiosity, an occaisional oil analysis might be interesting. A pretty well-done study is described at http://neptune.spacebears.com/cars/stories/oil-life.html. SAE document 2003-01-3119 describes some work done by Ford and Conoco-Philips that relates to it too. Both of these studies conclude that the greatest wear occurs right after an oil change. The SAE report, which you can get for $12, attributes this pattern to the removal, by the fresh oil, of some kind of protective film that builds on the wear sufaces in the course of using oil for an extended period. . The study at neptune just documents that the pattern exists. It looks like changing at the 3000 mile or so interval is a bad idea. Better to go to 7000-8000 at least. Maybe less for a worn engine. My GM 2003 vehicle tells me to change somewhere after 9000. > My independent GM mechanic, whom I trust, has recommended to me that I > use synthetic oil in my recently-purchased 2004 Impala, and use this mx [quoted text clipped - 5 lines] > > Jim Thomas > A pretty well-done study is described at > http://neptune.spacebears.com/cars/stories/oil-life.html. SAE document [quoted text clipped - 4 lines] > protective film that builds on the wear sufaces in the course of using oil > for an extended period. . No doubt that the additives work in the way you describe: A matrix or film develops on the surfaces. I have suspected that the introduction of air at the oil change time may be involved in the effect. Iron concentration seems to go up right after a change, which would be consistent with increased wear OR scavenging of the oxygen which was introduced. Just a hunch. >A pretty well-done study is described at >http://neptune.spacebears.com/cars/stories/oil-life.html. SAE document [quoted text clipped - 7 lines] >bad idea. Better to go to 7000-8000 at least. Maybe less for a worn engine. >My GM 2003 vehicle tells me to change somewhere after 9000. My car manual divides driving into *severe* and *other* Severe being a lot of short trips, stop and go, city driving, driving in dirty/dusty environments, pulling a trailer, etc etc. Under *severe,* more frequent oil changes are recommended, and the number drops from your 9 billion miles down to 3,000 miles. Some of us haven't forgotten how to read. Lg >> My independent GM mechanic, whom I trust, has recommended to me that I >> use synthetic oil in my recently-purchased 2004 Impala, and use this mx [quoted text clipped - 5 lines] >> >> Jim Thomas "Your 9 billion"? I don't understand your smart-assed post. For someone who claims to be able to read, 9000 is not 9 billion. And there's really no reading to it in my case. My oil light comes on sometime after I've driven 9,000 miles since the last change. >>A pretty well-done study is described at >>http://neptune.spacebears.com/cars/stories/oil-life.html. SAE document [quoted text clipped - 31 lines] >>> >>> Jim Thomas > "Your 9 billion"? I don't understand your smart-assed post. They: 1) Misread 2) It's a joke. Don't take everything so seriously and rant on it. And please don't top-post - fix your borked OE.  Signatureremove MYSHOES to email Laurence has a habit of believing what is written in his owners manual and sometimes thinks that it also pertains to other people's cars. The idea that new oils, new engine designs, and new computer technology might allow people to do other than follow the old wives tale of "change the oil every 90 days/3000 miles" is tough for some people to grasp. And I hate bottom posters - particularly ones (not you, to be sure) that post a non-comment at the bottom of some extremely long thread and don't have the courtesy to clip the thread. If I see a top post and I'm curious about the rest of the thread, I can scroll down. Usually, I'm reading the thread consecutively so I already know what's down there. Top posting is the best way for me... Brian >> "Your 9 billion"? I don't understand your smart-assed post. > [quoted text clipped - 5 lines] > > And please don't top-post - fix your borked OE. "Brian" <brian.evans@mci%%%.com> wrote in message news:O2a6f.396$43.128@nnrp.ca.mci.com! If I see a top post and I'm curious > about the rest of the thread, I can scroll down. Usually, I'm reading the > thread consecutively so I already know what's down there. Top posting is > the best way for me... > > Brian Totally agree, Brian. There is nothing inherently wrong with top-posting, and I usually find it very convenient to read. There was never any sort of law against it, just recommended practice. Some people organize their files in folders with the most recent first. Others see it like a book, where the beginning is page one and you file to the back. At the end of the day, it doesnt make a damn. >Laurence has a habit of believing what is written in his owners manual and >sometimes thinks that it also pertains to other people's cars. The idea >that new oils, new engine designs, and new computer technology might allow >people to do other than follow the old wives tale of "change the oil every >90 days/3000 miles" is tough for some people to grasp. This is true. However, unless you are actually doing an oil analysis (and a lot of truck places and fleet maintenance places will do an oil analysis for you, and it's not expensive), you don't really ever know about the condition of your oil. Modern oils do some things very well, and the synthetics don't have anything like the breakdown and varnishing problems of older oils. So if that is the limiting factor, you can run oil for a long time without changes. If, on the other hand, the limiting factor is buildup of combustion byproducts, the newer oils are only a little bit better than the old ones at keeping the junk in suspension... and it still builds up. If you don't do the analysis, you never know. And if you don't know, it is best to play it safe. Oil is inexpensive. Engines are expensive. --scott Signature"C'est un Nagra. C'est suisse, et tres, tres precis." > This is true. However, unless you are actually doing an oil analysis (and > a lot of truck places and fleet maintenance places will do an oil analysis [quoted text clipped - 11 lines] > best to play it safe. Oil is inexpensive. Engines are expensive. > --scott Oil analyses are not very expensive, and I guess are better than nothing. I do not have a lot of faith in them. But you are very right ...lubricants are inexpensive and engines are very expensive. Premium filters are dead cheap (if we can find out which is a premium filter and which is an old sock) in the scheme of things. > Modern oils do some things very well, and the synthetics don't have anything > like the breakdown and varnishing problems of older oils. On the other hand, they're starting do do a very few things poorly. Most modern engines lack a few friction mechanisms that were present in older vehicles: modern cam followers are almost exclusively roller type, which eliminates the extreme pressure point of a flat tappet sliding on a camshaft (the highest pressure wear-point in an engine so equipped.) Modern engines also typically don't have any gear drives at all, where as almost all older engines had at least a helical gear-driven oil pump and distributor and a few had gear-driven cams as well. Both flat cams and gear drives require certain additives to protect them properly, and these additives are DEcreasing in concentration in newer oils. They're also "depleting" addtives that are actually consumed from the oil as they do their job. Fortunately, there are still formulations around with plenty of those additives that can be used at extended drain intervals in older engines (Mobil-1 High Endurance, for example, which is why it receives an outdated API rating- it has too much of some additives to qualify for the latest rating). Oil isn't a "one size fits all" choice. Thanks to all of you for your interesting (and mostly applicable) inputs. One thing my mechanic mentioned to me, and which I didn't see mentioned in your posts, was that data he saw showed that synthetic oil reduces friction over dino oils, resulting in better mileage (something worthwhile thinking about in these days of $3.00/gallon gas). Have any of you seen data to back that up (or refute it)? Jim Thomas > Thanks to all of you for your interesting (and mostly applicable) > inputs. One thing my mechanic mentioned to me, and which I didn't see [quoted text clipped - 4 lines] > > Jim Thomas I have had people measure their mileage before and after changing to synthetic, and swear that they get a little better mileage. I believe I have seen some test data that shows a little better mileage can be expected in some conditions, but would have to search to find the report. I think it is probably true, in some cases. >> Thanks to all of you for your interesting (and mostly applicable) >> inputs. One thing my mechanic mentioned to me, and which I didn't see [quoted text clipped - 12 lines] > >I think it is probably true, in some cases. It could be true. But physics don't change at this *level.* Most of the energy expended by the gasoline goes into overcoming the inertia of the vehicle, and wind resistance. I think people can get better mileage just by being sure their tires are properly inflated. IOW, I wouldn't switch to synthetic -just- for that reason alone, unless I could be convinced it would pay for itself with the money saved on gasoline. Lg >Thanks to all of you for your interesting (and mostly applicable) >inputs. One thing my mechanic mentioned to me, and which I didn't see >mentioned in your posts, was that data he saw showed that synthetic oil >reduces friction over dino oils, resulting in better mileage (something >worthwhile thinking about in these days of $3.00/gallon gas). Have any >of you seen data to back that up (or refute it)? I think the mileage improvement due to reduced friction is going to be so small it'll be unnoticeable. On the other hand, the improved solvent action keeping your engine cleaner might improve mileage also. --scott Signature"C'est un Nagra. C'est suisse, et tres, tres precis." > Thanks to all of you for your interesting (and mostly applicable) > inputs. One thing my mechanic mentioned to me, and which I didn't see > mentioned in your posts, was that data he saw showed that synthetic oil > reduces friction over dino oils, resulting in better mileage (something > worthwhile thinking about in these days of $3.00/gallon gas). Have any > of you seen data to back that up (or refute it)? There is no basis to this claim. It is possible that some synthetic oils provide better mileage than some conventional oil, but the opposite claim is also true. I do believe that if you are in an extremely cold climate, synthetics might provide slightly better gas mileage because of better low temperature performance. However, once the engine warms up, the advantage disappears, so unless you are doing a lot of cold starts in a low temperature environment, I doubt you could see the difference. The API test for qualifying for the energy conserving mark involves comparing the oil being evaluated to a reference synthetic oil. To get the energy conserving mark, an oil must provide better economy in the test engine (a Ford 4.6L I think) than the synthetic reference oil. I personally have compared Mobil 1 5W30 to Havoline 5W30 in two vehicles. I ran both oils for many thousands of miles and then compared the cumulative fuel mileage (I keep a gas log) for each type. There was no difference (none, zero, zip, they were the same). I am in a relatively mild climate and do a lot of moderate to long trip driving, so someone that does a lot more short trip driving in relatively cold climate might have slightly different results. It is my opinion that you will not reduce fuel economy simply by switching from conventional to synthetic oil if you keep the same viscosity rating. Friction reducing additives are more likely to have an effect on fuel economy than just changing the base stock (assuming the viscosity is the same for the two base stocks). Regards, Ed White > Thanks to all of you for your interesting (and mostly applicable) > inputs. One thing my mechanic mentioned to me, and which I didn't see [quoted text clipped - 4 lines] > > Jim Thomas If there is an effect, it would be very, very small. Probably not enough to offset the added cost of the oil. I suspect (just my hunch, no hard data to back it up) that any savings actually results from better viscosity stability rather than better lubrication. The fact that synthetic oils are so consistent allows them to flow well at lower temperatures and still protect at high temperatures, so that there's less extra drag when the engine is at less than its maximum temperature. >> Modern oils do some things very well, and the synthetics don't have anything >> like the breakdown and varnishing problems of older oils. [quoted text clipped - 7 lines] >as almost all older engines had at least a helical gear-driven oil pump >and distributor and a few had gear-driven cams as well. Yes, and that's becoming a problem. I have heard of a few cases where folks used modern synthetics on small engines with splash-plate oil systems. The improved flow characteristics of the synthetic oils means the splash plate can't grab any of the stuff to fling it up, and the engine is quickly ruined. >Both flat cams and gear drives require certain additives to protect them >properly, and these additives are DEcreasing in concentration in newer [quoted text clipped - 4 lines] >is why it receives an outdated API rating- it has too much of some >additives to qualify for the latest rating). I don't know what the high pressure characteristics of any of the new synthetics other than the Royal Puple stuff are, but the data sheets on them ought to have three-ball tests, and they shouldn't be any _worse_ than an older petroleum oil. On the other hand, why spend more money for something that is only just as good? And, of course, the ability of the synthetics to flow through tiny spaces is a good thing from the standpoint of solvent action and getting varnish and gunk out, a good thing from the standpoint of lubrication, and a really bad thing when it turns tiny gasket gaps into huge leaks. --scott Signature"C'est un Nagra. C'est suisse, et tres, tres precis." > My independent GM mechanic, whom I trust, has recommended to me that I > use synthetic oil in my recently-purchased 2004 Impala, and use this mx [quoted text clipped - 5 lines] > > Jim Thomas I have to ask on what he bases this recommendation. It certainly isn't found in the owners manual. Has he tested thousands of cars over hundreds of thousands of miles before publishing this revelation? If you really follow that schedule you will be adding up to a quart of synthetic every 3,000 miles anyway, so I'm not really seeing a whole lot of cost savings here. It sounds like a lot of trips to the mechanic. I would follow the recommended schedule in the manual at a minimum and do it more frequently. > > My independent GM mechanic, whom I trust, has recommended to me that I > > use synthetic oil in my recently-purchased 2004 Impala, and use this mx [quoted text clipped - 9 lines] > found in the owners manual. Has he tested thousands of cars over > hundreds of thousands of miles before publishing this revelation? I think he has seen data from various sources, but most of his advice rests on 30 years or so of GM experience. I have found, in other cases, that his recommendations haven't always followed GM recomendations, but made sense and worked for me. That's why I, and many others, keep going back to him. I asked the question on this newsgroup not because I didn't trust his judgement, but because I wanted to find out if those of you who maintain cars have other ideas. And it's always nice to instigate a discussion... > If you really follow that schedule you will be adding up to a quart of > synthetic every 3,000 miles anyway, so I'm not really seeing a whole > lot of cost savings here. It sounds like a lot of trips to the > mechanic. No, I buy the oil at discount and do the oil changes myself, and he knows it. > I would follow the recommended schedule in the manual at a minimum and > do it more frequently. I've never followed a schedule that said to change the oil every 7 or 8 thousand miles (as most did in the '80s and '90s), but changed oil (and the filter) every 3000 miles. I've never had a motor fail from wear (most recently, my Subaru Justy went 210,000 miles and my Lumina went 140,000 miles- both sold running well). So why should I change things for my Impala? I guess I just want to do the best I can, for this car, within cost reasonableness. Jim Thomas |
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