Interesting Auto-Rx Observation...

[damanwitdaplan]

Hiya all,

I finally gave in and ordered my first bottle of Auto-Rx and dumped it into my '04 Jag S-type after a fresh serving of my favorite Havoline 5w30. Cat's got 90K on the odo.

This is where it gets interesting. I have one of those trip computers that gives you instant MPG readings in real time as you drive. I had always seen the MPG's go to 99 (highest possible number) when I coast in neutral.

Immediately after putting in the Auto-Rx, I took the Jag out for a cruise and it felt nice and smooth. I was shocked though when I let it coast in neutral. What was always a 99 MPG was for no good reason hovering in the high 50's!

Why so? I don't know what to make of it other than for some reason engine operating efficiency has suffered, Can someone help? Better yet, can you chime in on this one Frank?

Thanx a bunch.

 

[Dr_No]

I see no way auto-rx could cause any change in mpg that much by thinning or thickening the oil
It would not be because of friction or anything because auto-rx does not change the oil, it uses the oil as a carrier.
It is most likely a probelm with a sensor or something

Just my 2c

 

[Gary Allan]

Find out how it calculates the numbers. I would have a very hard time believing that Auto-Rx had anything to do with it ...even on the tertiary level.

 

[Craig in Canada]

The realtime efficiency goes to max value because when coasting in gear about a certain RPM your fuel injectors are shut off entirely. Since AutoRX isn't in your fuel system and didn't remap your engine computer it's not likely at fault. Observe longer. I've found that generally engine computers don't shut down the injectors like this until it is fully warmed up. Maybe you were still running on a cool temperature map for some reason. If your engine temp sensor (not the same one that runs the gauge/idiot light) is flaky, it could cause this, but also never touched AutoRX.

 

[bmwtechguy]

I always had my best fuel economy with ARX in the crankcase, and that with SuperTech oil!

 

[Shannow]

bmwtechguy...when I added AutoRx to my turbodiesel before my last change, there was a noticeable change in the spooling of the turbo...for the good.

No change in mileage.

 

[allan5oh]

your engine will always be injecting some fuel, unless it's a diesel.

Try going coasting faster.

Better yet, try coasting from about 30 mph all the way down to 0.

Interesting enough, when I "idle" my 12 litre diesel at highway speeds, I get the same fuel mileage as my parents prius. In other words, my entire engine uses as much HP as their whole car!

 

[rustlerdude]

Kinda not true allan. If you are going down a long hill and you downshift the engine 'puter goes into something called "enleanment" which means it goes from closed loop mode (fuel econ)back to open loop mode and shuts down your injectors pumping tons of 02 through the exhaust....which is why it's in open loop. In a manual trans if you shut down the engine while the engine is in this mode you probably wont even feel a diff. If you have a carb, dont do it! Put the key back to runa nd boom goes ur mufflers.

 

[allan5oh]

The only gas engine that I know that will do something like that is the Prius.

 

[Trucku]

MY scanguage has showed over 100mpg easily coasting depending on how fast I was traveling(not in neutral).

Go faster... then coast