Ever since the weather has turned cold here, my MPG has dropped from the usual 23 MPG to near 20 MPG. I've also swithched to Amsoil synthetic near that same time so I am not sure what is causing the MPG drop.

 

Engine may be compensating for the higher air density.

-- Chris

 

The rolling resistance of your new snow tires will have some affect too.

 

Car takes longer to warm up when cold. All cars use lots of gas the first several minutes operating. More cold, more time to warm up, running inefficiently.

Yes, the car runs rich when cold. The unburnt fuel is passed to the exhaust where an air pump provides more oxygen before the catalytic converter. This gets the cat up to operating temperature more quickly. Big reason the car gets the ULEV rating.

 

I already know of 2 owners that switched back to dino oil from synthetic and saw a significant increase in their MPG. I have a feeling that the synthetic is causing the loss in the MPG.

 

Oh, it is definately cold here now, ice, snow, sleet. Driving the S is a bit scary but fun at times.

I'll be lucky to get 15MPG since I can go to work in 1st gear almost.

I'll am going to switch to Mobil 1 in the next oil change so lets see if that will have better MPG than Amsoil.

I have every data point imaginable on the S since driving it. If anyone is interested in my template, just let me know and I can forward it to you guys.

 

The oil is not the problem. Look elsewhere.

 

I beg to differ..

I have enough data to point the finger at the oil mainly. Even when it was warm, after the oil change I saw a drop in MPG. A one to two drop in MPG is no biggie but my economy graph is dropping and that is a

 

I have a strong opinion that your fuel economy is dropping because it's getting colder.

For model year 2001, the change to 5w20 oil will allow a vehicle manufacturer's overall CAFE to decrease by a very small amount, typically in the tenths of a mile per gallon range. 5w20 oil is a lighter viscosity than a 5w30 oil and therefore has less internal engine frictional losses, or less drag on the crankshaft, pistons and valve-train. This decrease in frictional power loss promotes increased fuel economy. This increased fuel economy is virtually undetectable to the average consumer without the use of specialized engine monitoring and testing equipment when compared to a 5w30, 10w30 or a 0w30 viscosity motor oil.

Here's another link:
http://autonet.ca/DriverSource/Stories.cfm...fm?StoryID=4227

 

Dunno, my S is only 4 months old, but got 9k miles on it. Geting colder now, and my MPG has droped bunches, with no change in oil type. I used to get 25-28mpg, but now im geting as bad as 19-23? I know this colder weather is forcing me to VTEC more, this car REALLY runs stronger in colder weather, im guesing my heavier foot is the culporate.

Steve
V8-What?