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Sedans Chevrolet Malibu Chevrolet Malibu MPG-Real World Numbers
282 messages, Last post on Oct 24, 2009 at 3:58 AM
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Replying to: malexbu (Oct 16, 2008 5:59 pm) There are plenty of posts about mileage continuing to improve up to 10,000 miles. So, I decided to evaluate mileage until then before using synthetic. I have had many cars that I never used synthetic in, so I see no reason to go to synthetic early. Break-in is the mating of the cylinder rings (oil and compression) to the cylinder walls, and insufficient mating results in oil consumption, blow-by, tighter clearances and lower MPG. In your case, 3000 miles should be a sufficient break-in period, but more may be better. Or, more may also be unnecessary. Since I can't say for sure, I have to make a determination. I think that by my mileage results (33+ under ideal highway conditions), the car should be already broken-in, but I am in no hurry to decide to discontinue the break-in process by going to synthetic after only driving it myself for 1000 miles. I based my opinions on reading and reasoning since I have never performed a controlled break-in experiment where engines were torn down after differing break-in procedures. So, please don't think that less of a break-in period is insufficient based on what I have posted. Some exotic engines come from the factory with synthetic oil, but I believe that they have a better engine building process and/or have break-in performed at the factory. I would like to know if anyone has kept records on MPG before and after switching to synthetic oil?
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Replying to: ohc6sprint (Oct 16, 2008 9:14 pm) see if there is an additional improvement. This is, obviously, a very reasonable intention -- and I am as interested as anybody in learning the results. So, if one would use synthetic too soon, then the friction reducing results would not allow the rings to seat through wear. There are so many opinions out there about the proper break-in procedure that one has to decide for themselves after doing their own research. See, when I switched to synthetic in my still very young Bu, I did a lot of reading about oils and break-in procedures and concluded that for modern engines, manufactured with extremely high precision, the old rules don't apply: there is practically no break-in period for them and the sooner you switch to synthetic, the better. There are plenty of posts about mileage continuing to improve up to 10,000 miles. Don't know... I am very interested in this topic but wasn't able to notice the trend in reported facts -- only the "I hope it will happen" one. Can't say I saw a meaningful improvement myself -- and I watch MPG carefully. What does matter a lot, are road conditions, temperature and the driving patterns. I definitely drive gentlier now than 30,000 miles ago. In your case, 3000 miles should be a sufficient break-in period, but more may be better. I suspect so -- haven't seen anything bad yet  I based my opinions on reading and reasoning since I have never performed a controlled break-in experiment where engines were torn down after differing break-in procedures. This is my point, exactly: few (he-he...) people have performed such experiments, so while the reported MPG numbers are very interesting, for those who care (and thank you for your meticulous report!), I am afraid your statements about the break-in period and processes cannot be reasonably substantiated -- they are a part of a mysterious legend. Could be true in the past -- doesn't mean it's true now. If there were a need for an extended break-in period (beyond the 500 miles the manual mentions), or special oil change considerations, they would be mentioned in the manual, as many other helpful things are. Nobody but the manufacturer has the resources and incentives to evaluate the engines' life -- and tear some apart in the process. I would like to know if anyone has kept records on MPG before and after switching to synthetic oil? Why, I did -- here are appropriate MPG samples for my two Malibus: -------------------------------------------------- Car 1 ----- 26.00 28.04 21.72 27.39 27.23 27.63 29.23 ----- 3138 miles: OEM -> Mobil-1 Synthetic 26.18 25.01 21.34 Car 2 ----- 27.25 24.54 26.30 28.02 25.96 23.30 ----- 5414 miles: OEM -> Mobil-1 Synthetic 25.62 24.82 27.89 25.06 24.95 -------------------------------------------------- Do you see a trend here? Neither do I...
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Replying to: malexbu (Oct 17, 2008 7:19 pm) Today, I made a 180 mile highway round trip and was eager to get over 30 MPG again. I was only averaging 28.4 MPG after 140 miles. I was on my way home and completing the leg that had a downhill bias. I got up to 30 MPG about 30 miles from home and then I hit road construction and sat for 15 minutes inching along. Needless to say, the whole exercise was useless as my mileage fell at that point and if I ended it at the road construction (30 MPG), then I lost the down hill leg of the trip. Since I am retired, no two tank fulls are similar. I don't travel the same roads to and from work every week. That's why I look for highway trips that can give me a maximum reading. If I can attain say 32 MPG a few times with 6000 miles on the car and still get 32 MPG at 10,000 miles, that will tell me that my MPG gains has leveled off. If I then switch to synthetic and can attain 34 MPG a few times, then that will be a meaningful improvement. If I still get 32 MPG while on synthetic, then I will conclude that synthetic may not be worth the cost. I may then look for other intangibles such as lower operating temperatures or increased engine life. But that is a topic that will need to be researched by me if MPG does not improve. It will take until the end of next summer for me to get that many miles on the car. A further note on today's trip. I was in the manual mode in 6th gear when I passed a car on a two lane road. I had plenty of room to pass but needed to pick up some speed as a vehicle came over a hill at me. I was not picking up speed and I punched it to get over without result. I still got over in time, but was momentarily disturbed at what would have been the outcome if I needed the "passing gear" to avoid the car. I then realized that when in the manual mode, there is no "passing gear" unless I tap the transmission down two gears. This was the first time that I was in manual mode and needed to pass someone quickly. This car is still new to me and I am still learning the nuances of this type of transmission. Needless to say, this will not happen again. I will either use the auto mode when passing or be prepared to downshift manually from now on. While I understood what happened, it was not soon enough to suit me. I mention this only because anyone who has and uses the manual mode may find themselves in the same situation some day. Perhaps this is addressed in the owners manual, I'll have to read it. |
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I just switched to synthetic in my '09 4 cyl on Friday at 1900 miles. I've been quite disappointed in fuel mileage so far. I've never gotten over 26 mpg so far. I went camping this weekend and my wife drove the car around town. When I got home, the DIC showed an average of 16.3 mpg. The one thing I have found interesting is that the calculator consistantly reflects better fuel mileage than the DIC. After I've had a chance to put a few tanks in now that I have synthetic, I'll post the mileage figures for before and after.
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Replying to: phil53 (Oct 19, 2008 5:43 pm) The purpose of doing a MPG maximizing test is to see if your fuel economy is off or if its your driving style. To me, highway driving is 100% highway, not 80/20 or any other combination. If you still can't get 33 MPG or better under ideal highway conditions, you may have to consider that your break-in period needs to be extended or that you have a mechanical issue with your engine. If you go to the service department where you bought the car, they may tell you that you need to drive 5,000 miles or more before they will look at it. They may also say that just to blow you off for 6 months. But to look at it from their position, some people drive with a heavy foot and in hilly areas or mix in congested areas and speeds under 40 mph and think that they should get the 33 MPG that the computer says. If you drive under 40 mph (not sure what speed that the 4cyl transmission downshifts from 6th gear) you are not driving in 6th gear and you mileage will be less. So, it will take some time for you to determine if you have a problem and if it is the car or the conditions under which it is being driven. One other thing to check is whether your odometer is reading correctly. I checked mine on a recent trip using my Garmin GPS which tracks miles driven and had 237.9 miles (car) vs 237.2 miles (GPS). You can also drive a highway that has mile markers and compare over 100 miles. Yours should be fine but you have to check all variables to know for sure. That is another reason that service departments may be reluctant to address MPG; the fact that they don't have the time to sort through all the variables that the owner could do. If it were me, and all the above checks out and if the car can't get the desired MPG, then I would go back to regular oil and extend the break-in period and see what happens. Good luck, keep us informed on your results. Oh, and one last thought: I was riding with a friend in his car with a trip computer and he told me that his mileage was the same whether he drove in the city or on the highway. I observed that the MPG did not change even a tenth over 20 miles. I asked him if he reset the computer after each fillup and he didn't know what I was talking about. Turns out that he had nearly 100,000 miles of driving in his data base, and as soon as I hit reset, the tripcomputer began showing results. So, I mention this only because you never know who reads these posts and their understanding of the variables.
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Replying to: ohc6sprint (Oct 20, 2008 7:45 am) So I don't expect to get 33 mpg in routine driving. But, on my other GM products (an Avalanche and a Corvette), I pretty regularly get the EPA ratings - and that under the old rating system. On this car, I'm not even matching the new ratings. I probably won't make a big deal out of it with the dealer. I do want to wait until I can take it on a road trip to see what my actual highway mileage is. I will mention it to them, though. I have a pretty good relationship with the dealer - owner, service manager, service writer, etc. They've always treated me well. I'll let you know how it goes. And I'll post the mileage - both DIC and calculator. |
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Replying to: phil53 (Oct 21, 2008 5:42 pm) You might give it a try...couldn't hurt.
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Replying to: ronbo10 (Oct 22, 2008 7:30 am) been coddling the thing too much, it would seem. I finally decided to do a few max performance accelerations (5 or 6 zero-to-sixty runs), and sure enough my mileage improved significantly thereafter. Interesting... Did you follow the New Vehicle Break-In instructions in the Owner Manual, (p. 2-21): Do not drive at any one speed -- fast or slow -- for the first 500 miles (805 km). Do not make full-throttle starts. ?
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Replying to: ronbo10 (Oct 22, 2008 7:30 am) |
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Replying to: malexbu (Oct 22, 2008 1:40 pm) the Owner Manual, (p. 2-21): Do not drive at any one speed -- fast or slow -- for the first 500 miles (805 km). Do not make full-throttle starts. Yes, as I recall. I tried to stay off the interstates etc. I'm thinking I had been perhaps gentle with it, to the extreme... Definitely no full throttle starts or anything of that nature. |
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