I had been driving my new 1.8 L automatic matrix for 5500 miles, and getting the advertised MPGs (28-32). I had my oil changed, and now I'm driving in MA (as opposed to NY or NC) and getting 28 mpg on 100% hwy miles... IF I'm lucky. I'm concerned someone did something to my car during my oil change. Aside from the obvious information (tire pressure, air intake, bad gas, and all the other little quick fixes), what could be going on? Has anyone else had this experience or heard about it? Any suggestions?
Tire pressure is a possibility especially if they were previously inflated above the recommended level. They may also have used slightly thicker oil (10W30 or 10W40 instead of 5W20) although that would only have a slight effect on mileage. Finally, MA tends to be colder than NC and most parts of NY. So the gas there might be formulated for better cold temperature starts at some expense in fuel efficiency. AIRC, it has been pretty cold in your area recently and that will reduce your mileage (more time for the engine to warm up, more idling time, and thicker air).
Tire pressure is a possibility especially if they were previously inflated above the recommended level. They may also have used slightly thicker oil (10W30 or 10W40 instead of 5W20) although that would only have a slight effect on mileage. Finally, MA tends to be colder than NC and most parts of NY. So the gas there might be formulated for better cold temperature starts at some expense in fuel efficiency. AIRC, it has been pretty cold in your area recently and that will reduce your mileage (more time for the engine to warm up, more idling time, and thicker air).
dont feel bad, i do a mix probably 70% city 30% highway and i get a whooping 17mpg avg, and i went from boston to NH and back, used a full tank last month and avg 25mpg 100% highway, i think its the winter thing but in summer i couldn't avg higher than 22mpg with probably 55-60%city and 45-40 highway. i drive a 2.4L i personally dont know how some people over in MO are getting like 35mpg or more doing city with A/C on. and i use syn oil, i tried 0w-20 and im trying 5w-30 right now, so far i dont notice the lower mpg...maybe its a winter thing
they probably lowered the pressure of the tires. have you checked them?
I haven't checked my tire pressure. I know that the 09 matrix has a sensor that detects if your tire pressure is too low. It happened to me once, and the tire pressure was adjusted, and it has apparently been fine since. Would that make a 4mpg difference?
Tire pressure is a possibility especially if they were previously inflated above the recommended level. They may also have used slightly thicker oil (10W30 or 10W40 instead of 5W20) although that would only have a slight effect on mileage. Finally, MA tends to be colder than NC and most parts of NY. So the gas there might be formulated for better cold temperature starts at some expense in fuel efficiency. AIRC, it has been pretty cold in your area recently and that will reduce your mileage (more time for the engine to warm up, more idling time, and thicker air).
Less mpgs in colder weather makes sense, but I haven't heard of that before. Do you have any reliable resources to support this claim... aside from good sense? Also, do you think it could make a 4mpg difference? I'd imagine it'd have to be happening to a lot of other people too.
I haven't checked my tire pressure. I know that the 09 matrix has a sensor that detects if your tire pressure is too low. It happened to me once, and the tire pressure was adjusted, and it has apparently been fine since. Would that make a 4mpg difference?
The tire pressure monitor system will only inform you if one of your tires are at a different pressure then the others. I think it has to be quite a difference too. For example If three of your tires are at 32psi, and one is at 25psi, the light will come on to inform you that you should check your tire pressures. Its too bad, some systems actually tell you the exact pressure in each of your tires. I dont know if it would make a 4mpg difference, but it will make a difference and it is worth it to check it out.
Also my milage varies between gas stations. I constantlly get good gas milage at Petro Canada, but I never get good milage at Shell.
If you have an early build 1.8 and it was low on oil/burning oil then maybe they did the ECU reflash that changes the Dual VVTI and has been reported to lower MPG.
I still have not had my ECU flashed and my oil gets about a qt low after about 3500 miles. But I still can get 35mpg on every tank for the past few months. I will get mine reflashed when I find a day to do it.
It's also possible that they used the heavier weight bulk oil? that might have affected it a bit?
tire pressure definitely affects mpg as well as handling. i get 22mpg city/hwy 50/50 in south florida with no a/c on. i used to get the same gas mileage on my 2004 nissan sentra 1.8L
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2009 Matrix S - Classic Silver Metallic
If you have an early build 1.8 and it was low on oil/burning oil then maybe they did the ECU reflash that changes the Dual VVTI and has been reported to lower MPG.
I still have not had my ECU flashed and my oil gets about a qt low after about 3500 miles. But I still can get 35mpg on every tank for the past few months. I will get mine reflashed when I find a day to do it.
It's also possible that they used the heavier weight bulk oil? that might have affected it a bit?
No, I'm assuming they didn't do that because it wasn't mentioned to me. They allegedly used 5w20... not sure what kind exactly. It was a toyota dealership oil change, so I figure they should have done everything properly... especially at the price I paid.
Tire pressure is officially not part of the problem. I finally checked it today... all are about 32psi or a tad more.
This seems really bizarre. It must be a cold weather thing (not including longer idle times to warm-up... I really don't sit around waiting for the car to warm up). It's strange I haven't heard of this before, and it seems no one else really experiences this.
I had my first oil changed at my dealer, and guess what oil they used, 5w30. Even though I asked for the correct oil the service guy blew me off said it doesn't matter? heh
If they logged all of your work then maybe it would show what oil was used and if they flashed the ECU in your service history.
It is absolutely the cold weather. We had a bit of a warm spell and my mpgs were up to over 30 again. It's amazing that cold weather makes a 4 mpg difference. Thanks for everyones help!
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09 Matrix decreased MPG after first oil change!
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