Did my oil change affect my MPG?

Probably wouldn't hurt to check level to verify it wasn't significantly overfilled...happens fairly often.

 

I believe many have found that if the oil is overfilled the crank slaps it, foaming it and causing a number of problems, including poor fuel economy.

 

thicker oil maybe?

 

You switched to a slightly thicker oil (the spec'd oil, btw). It will be a factor, not sure how much.

"local franchise" is Toyota dealership, quicky lube place?

 

Assume you're using AC then?

 

I would say it doesn't look unreasonable for a hot summer with AC use, a thicker oil, and possible crankcase oil slap. If it is overfilled, it's not really damaging anything, although I believe the crankcase slap can cause some cavitation which theoretically far down the road could cause metal wear, but that's not really something to worry about. The main issue is just if it is still overfilled, it will continue lowering your fuel economy. All that would need to be done is remove some of the oil, either by using a syringe down the dipstick tube or by loosening the drain plug and letting about 2/5 qt drain out.

 

Check the oil level first, resolve whether or not its overfilled? I suspect it's not, but let's check.

 

Yes, first step check the oil level.
Yet OP mentions significant drop.

AC use and tire pressures would be my thoughts.

Yet, going further maybe brake drag?
Maybe less efficient brand of fuel or winter to summer fuel formula changes.
Dirty air filter or intake leak or not running on all cylinders? (Quick Lube mistakes)
20 weight vs 30 weight hot....maybe but I would not have thought significant mpg loss.
0 vs 5 is for cold again, I would not have thought significant mpg loss.

Let us know what you find.

 

That wouldn't be a factor. There's nothing about a Fram oil filter that would affect gas mileage.

 

Your very fixated on the oil over many posts.

Dealer oil changed all its life it has seen some god awful cheap oil and has been routinely overfilled. That's why the dipstick looked so bad
in your other posts. Really crappy oil.

Throw the dealers the keys and say change it you get the vat oil. But usually some donuts.

Mileage is bad because unless the hybrid battery has been replaced its way way way overdue to be replaced. This forum has hundreds of posts about failed or failing hybrid battery and how to service them. Start reading your going to need it.

The cars power comes from the hybrid battery. Poor mileage because you have to push the gas pedal more and more to get the car going because the hybrid battery is contributing less and less propulsion power.

Go to toyota.com/owners forum and join. Have your insurance card handy as they will ask for the vin.
Once joined go to the service forum and you will see every instance that car has had service at an authorized Toyota dealer.

You may see why it was sold or traded in.

Start watching the battery monitor screen on the mfd for the battery's behavior. Note how many times it goes to one purple bar and how fast it will go from a good 2 blue bars to a bad one purple bar. How often the engine comes on when its sitting. If your sitting and the engine is running that means the battery needs a charge. Not good.

Lots of purple bars or worse no bars just white screen is very aged battery.

Howe much did you pay for the car?

 

Oh and Jiffys database shows the Prius G2 takes 5 quarts.

Its takes exactly 3.9 quarts with new empty oil filter so your a quart over filled. I have changed the oil on my g2 maybe 30 times.

Nothing under the table about bringing your own oil I used to do it all the time at Jiffy they don't care.
Go online look for a coupon and bring them 4 quarts of oil and a new filter. Mine charges $20. labor. I don't let them touch anything else. I stand there and watch them.
When I give the guy under the car changing the filter I duke him $5 and tell him not to go crazy on the pan bolt please.

But your only going to bring your own oil if its better then what they have in your case just have them put cheap 5-30 oil in it. I'm pretty sure your engine eats oil bad.
Synthetic is a waste of money at this point. Just tell them to put 4 quarts in it.

Haven't been to Jiffy in a long time since found a good shop that likes cash. They let me under the car when they work on it. All you got to do is duke 'em. They see me coming and wave me right in lol....

You really need to see whats under the car. How rusted it is. Whats leaking. Whats just dried up ready to fall off. Especially a 16 year old car.

if you ever get a chance to get under the car on a lift take alot of pictures of everything under there with your phone.