low mpg mystery

I've got a '96 camry, 145k miles, that gets about 22 mpg (mostly city). I'm wondering why it's so low. I even filled up with 2 full tanks of Chevron, hoping to clean the fuel injectors.

Tires are properly inflated, tranny and diff oils changed as per schedule, spark plugs changed recently by me.

Any relatively cheap checks I can do, to try and increase efficiency? We're a little undecided whether to keep the car or buy a Sienna, so I'd like to keep major maintenance labor to a minimum.

Thanks,

Michael

Reply to
mrdarrett
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I think the mileage you're getting is normal, assuming you have the 4 cyl 5SFE. If you want to improve it a bit, you could try adding 4 psi to the tires but monitor the wear with a gauge to make sure they're not wearing too much more in the middle.

Reply to
Nobody Important

did you check engine timing , a old streched belt can loose you 4 mpg, synthetic in motor differential and trans can get you 4-5 mpg, cleaning the rotor and cap or new wires, oxygen sensor, will help but

22 city seems normal
Reply to
ransley

Compared to what - wet cement? Even the Amsoil wacko aren't going to claim a

4-5 mpg improvement. There is no reason to think that synthetic oil of the same viscosity as conventional oil will improve the fuel economy at all. In fact, the test to certify any oil as energy conserving II compares the oil being evaluated to a PAO synthetic oil. To get the energy conserving rating, a 5W30 oil must get 3% better mileage than the reference 5W30 PAO synthetic oil. To be sure, the synthetic oil is formulated without special friction reducing additives.

If there is a fuel economy advantage with synthetic oil, it is that the stability of the synthetic oil allow it to maintain it's viscosity longer. All oil thickens with time and mileage. As the oil thickens, it will reduce mileage, but only very slightly. Ford and others (Toyota and Honda) that switched to 5W20 oils are claiming less than a 0.5% (that is one half of one percent) improvement in fuel economy as a result of that switch. Synthetic oil is fine stuff, but there is no way you are going to get a 4 to 5 mpg improvement unless you were doing something very wrong prior to making the switch.

Ed White

Reply to
C. E. White

== My '94 gets the same. Not much can be done to improve it apart from buying a Corolla, Echo, Prius, or Camry Hybrid -- all of which will cost far more than what you're paying in fuel now. When I'm on the freeway more, mileage rises to around 24-25, and on the rare occasions where it is all freeway driving I've seen 30 mpg. (US) or even slightly higher. If you could ever find a place where you could drive a full tank through at 55 mph., you'd probably see 32 mpg or even slightly more. With the traffic in my area, coasting and driving gently aren't really possible, but those are the techniques that increase mileage. Check to make sure the car rolls freely on a gentle grade to see that the brakes aren't dragging, or caliper binding. Otherwise be glad you're getting 22 city. I think the original sales brochure for my '94 listed the EPA city at 18 mpg.

Reply to
Daniel

Ok, thanks for the tips, everyone.

My wife's '99 gets over 25 mpg city driving... then again she's a new driver and she drives super-cautiously. So I thought something's seriously wrong with my '96.

I'll look at the spark plug resistance. I changed the drive belt myself - just removed and put a new one on. I don't know how to check the timing yet - would changing the drive belt muck up the timing? (I made sure none of the wheels the drive belt was on moved when I changed it.)

I am using a bit of oil - maybe have to add 1/2 quart every 3-4000 miles or so. Bad sign?

Michael

Reply to
mrdarrett

Well CE white, try it or keep your wet cement.

Reply to
ransley

Forgot to mention, it's a 4-cylinder, being driven in flat Sacramento. (No hills to speak of here.)

Michael

Reply to
mrdarrett

I assume you are replying to my comment that synthetic oil will not lead to a measurable mileage improvement in most cases. The fact is, I do use synthetic oil. I also keep very detail gas record. When I switched to synthetic oil there was no measurable change in fuel economy - zilch, zero, nada, none - at least to the precision of my record keeping. I think synthetic oil is good stuff, but unless you are changing viscosities, there is no reason to expect a measurable improvement in fuel economy. People that make wild claims about great increases in fuel economy by switching to synthetic oil are either poor record keepers, or made some other significant change (and I mean super significant change). If changing to synthetic oil would result in a 3 to 4 mpg improvement, all cars would come with synthetic oil. Ford changed from 5W30 conventional oil to a 5W20 synthetic blend oil just to gain a 0.3% improvement in fuel economy.

The most radical claim I can find for synthetic oil comes from those fine folks at Amsoil. They say:

"Maximizes Fuel Economy

"AMSOIL Synthetic 5W-30 Motor Oil is designed to maximize energy efficiency for improved fuel economy. Unlike conventional oils, its uniform molecular structure helps it flow more freely and reduce friction between metal surfaces. Anti-friction additives are included to further improve energy efficiency."

This is typical Amsoil hyperbole. They don't actually say anything that is untrue, but then they don't really say anything at all. I love the statement - "its uniform molecular structure helps it flow more freely." Viscosity is a measure of how well the oil flows. So there is no reason to think Amsoil 5W30 oil flows any better than someone else's 5W30 oil, unless the Amsoil 5W30 is really 5W20......

It is the anti-friction additives that make one oil more fuel efficient than another of the viscosity rating. In an EPA test, PetroMoly Oil was actually found to improve fuel economy. This conventional oil includes a lot of anti-friction additives. Even this oil only provided a small improvement in fuel economy (3% or so). And it is not API certified. There is a good change constant usage of this oil would damage a catalytic converter. And in fact the oil is no longer marketed, although an additive is (there is not an EPA test of the additive).

Ed

Reply to
C. E. White

Reply to
ransley

When I change at 5000 every time with mobil 1 5-30 I notice the difference in driving, when I drain out the trans at maybe 15000 I notice a big difference shifting, The differential I noticed a minor difference. When I change I notice a mpg increase, I believe the anti friction additives wear or are cooked out, Change everything to mobil one synthetic, Motor , trans, and differential, I believe you will see what I have found, a noticable difference, a difference I see at the pump in mpg increase, which goes away slowly over the next 5000 miles.

Reply to
ransley
25 is actually pretty good for city. 0.5 quart every 3-4000 should still be fine. What weight? 10W-30? That's what I use.

Reply to
johngdole

I second that!

Ideally you should notice as little difference as you can without using too short of an interval. IMO if you really notice before/after change it's overdue.

That's how I got my oil intervals down to 3000 miles (dino 10W-30, Purolator PureOne or Bosch Filtech). And tranny's GM-Dexron III fluid at 7500 miles and strainer (Fram ATF kit) 15,000 miles.

Reply to
johngdole

Im sure its the interval but with mobil1 I leave it till 5000m

Reply to
ransley

I'm using 10W-30. I even tried 10W-30 in my wife's '99, hoping it would clear up the blue smoke startup, but the smoke's still there. Oh well.

Got about 29 mpg on mostly freeway driving (with some city). I guess those city miles with the A/C on didn't help any.

Still lower than my wife's '99, where she got 31 mpg freeway on at least one occasion. (But she was running 5W-30 that time.)

Thanks,

Michael

Reply to
mrdarrett

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