friendly_jacek

One more think, before declaring a great deal on this car, investigate the head gasket, as many used subarus for sale MY 1997-1999 have HG problems.

I'm surprized it was clean like that. When I changed front/rear diffs factory fluids at 40000, they were black from metal particles. I thought it was normal from the brake-in. Am I wrong? BTW, I put in Redline 75W90.

flashing MIL/CEL means serious and continous emission problem, posibly leading to damage of engine or cat. I would not drive it before fixing the problem. Sounds like the car was much neglected and with no maintanance whatsoever.

Nipper, what was the purpose of your post? I didn't get it. If you red carefully the stuff i quoted, you would see that the quote is about the catalist metals inside OXYGEN SENSOR and not catalytic converter.

In the light of the new facts I learned about acetone (see the other thread on acetone), your findings totally make sense. You used to get 23 mpg with 90% hwy driving at 65-70. This was way poor mpg for that speed. I get 26 mpg with 75 mph driving (AC off) in my 2000 legacy. My guess is that your engine runs very rich and your o2 sensor or some other emission sensor is way off. Now, the acetone leans out the mixture via chemistry on the o2 sensor and you are beck to where you are supposed to be. According to my quick search, the acetone trick works only on older subarus, pre 99, that had different o2 sensors and possibly were fuealed too rich.

I found some evidence to suport my claim from http://www.chemicalforums.com/index.php?board=5;action=display;threadid=2517 "The vapor/surface tension "thing" just doesn't hold up for about 12.5 reasons (basic, surfactant chemistry). :"They" had the same "discussion" back in the 80/90s when gas was expensive (supposedly) and catalytic converters and oxygen sensors were starting to come in to use. FYI: The acetone is reacting with the catalyst used in the oxygen sensor making the mixture appear" too rich. As a result - the mixture is leaned out by the computer thus the mileage goes up. The reason it does not work the same on all cars is that there are three different metals used as catalysts in O2 sensors: platinum palladium rhodium or in combination. Acetone in combination with NOx (and others) in the exhaust will react differently with each metal to either speed up or slow down the catalytic reaction of the oxygen senor. FYI, I am not talking about the catalytic converter - just to stop about 100 posts. Question: am I the only one on the planet who remembers this? There seems to be a lot of people skiing behind the "vaporization" boat? The reason I know this is that I used to work for Exxon; and fyi, the reason they don't put acetone in gas is that it is hard to get it to stay there and second over time it reacts with different kinds of additives in fuel. Which is also a reason why it does not work on some cars - it's the gas not the car. They have had additives in the past with acetone - old news. It is good that it works though! It simply had gotten more news because of the historic price of gas. Also, this is why ASME standards for elastomers used in cars requires (heavily suggests) that all elastomers be tested with acetone - along with other (i.e . MTBE, M85 ...) Once again, very old (but good) news (remembrances)" If the acetone is indeed affecting the o2 sensor, it would explain why only small amount would have a big impact. Furthermore, for the acetone reaching the o2 sensor, there has to be incomplete combustion and the car has to run very rich. Then leaning the mixture would indead improve MPG. Sounds like the acetone trick is a crutch for failing O2 sensor. People with well tuned car will not see a diffrence, unless there is a placebo effect.

Since I posted this (mind you, this was in 2005), I tried acetone in both my toyota and subaru for 1 tank each. No difference in MPG. The people reporting improvements have either placebo affect, cleaned their engine, or have the car seriously out of tune. However, the people claiming that 0.3% acetone will blow up the car are clueless.

The hydrogen idea dosn't make sense conceptually, but supposedly works by faster combustion of the hydrogen effectively advancing the timing. I discovered this great site that reviews the various "fuel saving" gadgets. There is also a case study on acetone. I think this guy hits a nail: http://www.fuelsaving.info/debunk.htm

And finely, there is a special procedure for burping the cooling system of phase 1.

It is weird how acetone works for some and not for others. This test shows no effect of acetone: http://www.hydrogen-boost.com/july%202005.html There is a link here where someone got lower MPG with acetone: http://townhall-talk.edmunds.com/direct/view/.ef047b3/739 When I did some research on this I found an official spec sheet for gasoline in India that gave a maximum limit (very small fraction of percent) for acetone in gasoline that suggested to me that acetone is not a desirable compound. The issue of reseting ECU before testing is a nonissue as ECU relearns fuel trims within minutes.

Is this pure hwy driving? I tried in city and there was no difference whatsoever. Are you saying that you get 23 mpg regularly and now, with the same driving style and speed you get 29? This is remarkable. Maybe you just cleaned the injectors?

If you are refering to the dexcool orange formula, it is very bad and dubbed deathcool: http://www.consumeraffairs.com/automotive/gm_dexcool.html However, not every orange coolant is dexcool. My 2000 lagacy come with orange coolant from the factory. Now it has green subaru coolant.

To test the pump/pressure regulator combo, you need fuel pressure gauge, $30-50.

This is good info for generic O2 sensor. However, the 2000+ subarus have WIDEBAND sensor also known as A/F ratio sensor. It doesn't switch around 0.45V like the traditional sensor but rather keeps slightly wavy almost streigt line on oscyloscope or OBD2 interface, its near 4V. Hard to interpret if the sensor is borderline. Believe me, I went through the whole learning process when there was little info available on these new sensors.

You mean it was replaced december 2005? If so, unlikely that the sensor went bad that fast unless was bad from factory. I don't know what to tell you. I suffered 16 mpg in city for long time since there were no codes and the O2 sensor seemed OK on the OBD2 scanner. As soon as the part was replaced, the city mpg went from 16 to 19 and hwy from 24 to 26. Mind you I paid $150 for the part. Now you can have it for $80 at the dealer. With this good price I think it's no brainer, in the worst case you have a spare part. These new style wideband O2 sensors are sure very fragile.

How does one inspects fuel filter? The standard maintanance is to replace it every 30000 miles and not "inspect" it. If you follow your logic, why fuel filter would not stop crud from reaching the injectors?

Check you wheel bearing. 23mpg and complaining?

Amsoil is a very good product, but the type of marketing they use, like you just mentioned above or hyping 4 ball scar values (that applies to ball bearings wear but not combustion engine) amounts to brain washing of gullible customers. For that reason alone I stay away from Amsoil products. Like it was said above, ANY modern oil, 10W30 API: SL or SM, including $0.59 special, will give you more than adequate protection for at least 5000 miles or 6 months. It you drive in arctics, tow, drive 120+ mph in hot climate, or want to change oil only once a year, look for better oils. Caveat: not every oil marketed in US as "synthetic" is realy good. "ACEA:A3" or "API:SL/CI-4+" certification is the guarantee that you are getting the best possible oil to protect the engine under heavy service.

How do you know if it's injector problem? Have you ever replaced the fuel filter?

google or search button on this forum is your friend.

I don't believe anything can beat BR-3 value and performance wise: http://www.obddiagnostics.com/ As for your MPG problems, replace front O2 sensor. It was recalled in 2001 because it had numerous failures. Unfortunately, the replacement part is the same bosch sensor! I also have 2000 legacy, had the 2001 recall done at 20,000 miles and replaced again in 2005 (60,000 miles) due to getting 16 MPG in city. Mind you, no codes or major drivability issues, but the car run rich.

Its simple: synthetic base doesn't mean less wear under normal conditions. Wear depends mainly on engine design, materials, temperature (more wear in cold) and antiwear additives in oil. Regular oil with robust antiwear additives (ie heavy duty oil) will give you less wear than light duty synthetic oil (lets say most mobil1 or syntec oils). Except, under very low or very high temps where synthetics or even semi-synthetics (group 3) shine. Edit: in the typical driving conditions in US, it really doesn't metter much as drivers rarely tap more than 50% of the engine potential, even with Hwy driving.

The most ridiculuos thing I ever heard about frequent oil change. Do you drive 7500 miles per month? Quality regular oil is good for 5000 miles (city or mixed) or 7500 miles (hwy only) or 6 months whatever comes first. Good quality (heavy duty) synthetic is good for up to 15000 miles or 12 months. Not every oil marketed in US, including pseudosynthetic ones, is quality heavy duty oil. The above link covers it well.

Are you absolutely sure it's the gas? As ambient temps are increasing, that alone could increase the MPG (oil less thick, less friction in the drivetrain, shorter warmup, increased pressure in tires). On the other hand, it could be fuel with increased BTU or increased cleaning power cleaning your engine. Ethanol has variable effect on MPG but usually a decrease as 50% lower BTU of alcohol compared to gasoline.

Both 5W40 rotella and 5W40 mobil1 (aka delvac1) should be available at Walmart.