I was reading a thread about engine running temp and improved mileage and got to wondering about this issue while using biodiesel. It is my thought that BD runs cooler than #2 due to the lower BTU content by comparison. I may be wrong here, but that's my perception. So, would using one of this 203* thermostats improve MPG using BD?? I don't know...has anyone tried this or looked into this issue?? Plus, I use my truck for pulling a big 37' 5th wheel, so it's primary use is for heavy loads. So, would this thermostat be even better in that situation to run the lower BTU biodiesel when pulling loads??
I also got to thinking if this cooler running temp might be one reason BD tends to give slightly lower MPG...what do you think??
Here's the thread link...actually, there are two links discussing this, so I've included both.
In my experience fuel economy is largely a matter of perception. I've tried just about everything, including a 203 t-stat, and while I'm thinking about improved economy my driving style adjusts and I get improved economy.
Funny thing is, when the new wears off and I get back to my "regular" driving style, my fuel economy returns to it's previous state. The nice thing about that is my truck got ~17 mpg stone stock, and now 176,000 miles and an additional 200 horsepower later......it still gets ~17 mpg.
The bottom line is....if you want better fuel economy you have to drive slower, feather the throttle, baby the rig....etc. etc.
According to the chevron site. Expect a 1 to 2% lower MPG with the reduced BTU's in the ULSD.
I agree that driving habits have a lot to do with MPG. For example if we keep our foot out of the IP and drive a grandpa 55 instead of 75-80 you'll see a marked difference in MPG. I tried this for 200 miles and there was about a 4 mpg difference. We got 20 MPG on our 04 instead of our usual 16.