1st oil change no MPG increase?!?

speaking purely for myself only I can suggest that you:

1. boost air pressure in the tires. 42/40 is where I am going.

2. slow the heck down! 75+ is illegal almost everywhere! Try 55 or 60. You would be amazed at the mpg difference.

 

Nope, that's about it for oil. Higher tire pressure should help noticeably.

 

All I can add to this is that in the very limited experience I have driving at those speeds, FE in the low 40s is about right, synthetic oil or not.

This is about aerodynamics not the mechanical workings of the engine. I wish I could remember the thread on here where I read this so I could give credit where it's due, but I can't, so kudos to whoever said this first.

Imagine the following:

• You have a bucket of water.
• If you take your hand, spread it as wide as you can and then very slowly press your palm down into the water, the water moves out of the way and you hand goes into the water with no problems.
• Now, imagine taking your hand, again spread wide, raising it over your head and slamming it down onto the surface of the water. You can probably predict what's going to happen: one, water everywhere, two your hand is going to feel like you just slapped a brick wall.

Those two results are representative of any object moving through a fluid environment. Yes, for this purpose, the gas in the atmosphere around you can and should be considered a fluid, just like the water in the bucket in the analogy.

At lower speeds, even objects with relatively high drag coefficients (i.e. your spread-wide hand) will pass with little resistance. However, at higher speeds (i.e. you trying to spank the water), the fluid properties change and it does become rather like hitting a brick wall; you’re literally trying to force the fluid out the way rather than letting it flow around the object.

The place where that transition (from flow to force out of the way) occurs is a property of the fluid, not of what you're trying to move through it (yes shape does have some mitigating influence, but it's not huge). It turns out, that for air the first such transition is around 55 mph.

I know, everyone hates that number. The "man" didn't make it up to get us to all conform. It really comes from the simple fluid dynamic principles. Yes, there are other transition speeds for air, but unless you're talking about delta-winged aircraft, they're not important.

You might get small gains by changing mechanical things about the car (your oil, etc), but until you accept the reality of physics, you're not going to see big gains. Like most things in life, FE isn't free, you can have it, but to get it you have to give up some driving habits that probably aren't very good anyways.

Ask yourself this, if you drive 20 miles one way to work every day, how much longer does it take you to travel that distance at 60 mph as opposed to say 75 mph?

Do the math. The answer will surprise you. (To get time in hours, divide your distance in miles by the speed in miles per hour. To convert time in hours to time in minutes multiply the fractional number of hours by 60.)

 

Many folks (myself included) experienced a drop in mileage after the first oil change. The reasons? Could have been too much oil or it could have to do with the tire rotation. Sometimes the tires are a bit "sticky" at the beginning, so mileage often will increase with greater tire wear.

Maybe you've just conquered the MPG drop by improving your driving techniques!?

 

I moved to Mobil 1 at 1000 miles and have never seen an increase in mpg with an oil change. Have tried 10-30 and then moved to 5-30 with no difference in mpg's. Now tire pressure is 5 mpg's one way or the other.

 

There is no magic formula you can pour into the engine and get better MPG.
If your goal is truely to increase your gas mileage, then you must slow down. Get out of the left lanes and discover a new, slower paced and better life in the right lanes.
Pump up your tire pressure.
Learn to manipulate your Prius at will, with Glide, stealth and warp stealth techniques.

Have fun

 

You are in SoCal so I would assume that you should at least be getting 50 mpg and up. The fastest I go on my Prius is 70 mph and my average is staying above 50 mpg. So, slow down a bit. You'll see the difference.

 

I have a unconfirmed theory:

According to unverified sources, the prius is filled with 0w20 synthetic at the factory.
It's a fact that synthetic oil can last for at least twice the change interval (10,000 miles) according to various used oil reports posted here.

So you shouldn't notice any difference if you use a synthetic oil replacement. However, when people use conventional oil as their first oil change at the dealer, they get a drop in mpg because conventional is less slippery. (plus it may be overfilled)

Thats my current two cents anyway

 

KANDYREDKOI, i changed my oil at 1800 miles.....when i did so, i had a very reliable source tell me that the 08 engines are built at a much tighter tolerances than the years before. now, same engine, same this and that, but the tolerances are much tighter. so, in turn, he suggested that i use lighter engine oil. NOT being able to find the 0-20, i just went to PEPBOYS and got MOBIL1 5-20W. ***********when i did this, i saw a good increase in gas mileage, somewhere between 3-6 more mpg, i used the stock, factory oil filter.

now, on the same subject, i heard that the tourings do loose 1-3 mpg versus the stock prius's due to the tire/rim combo. **********i regretted NOT getting a touring, and there are some touring TC's here that get better than my mileage, so this could or could not be true.

then, i would suggest that you read dr. fusco's suggestions on actually driving the prius with fuel efficiency in mind. it's a very good article and it will definitely help you get better fuel efficiency.......

PUMP UP THE AIR ON THE TIRES!!!!

last but not least, challenge yourself to drive the energy screen and/or consumption. keep the mpg as high as you can. when you see the gauge read 25 mpg on the freeway at 75+ mph, slow the heck down and get it to 50mpg or even 75 mpg. accelerate only when needed and hold the throttle steady to get the most efficient mpg. just try this for one week and let us know your results.

good luck!!!!!!!!!