Fuel Economy Question

check the oil level on the dipstick. they sometimes overfill and this can lead to poor mileage. also, check tyre pressure, they sometimes let pressure out of tyres. all the best!

 

Dealers change tyres air pressure for a softer ride, check tyres. I run 42 psi front and 40 psi rear. Do not go higher than max psi on the side wall of the tyre.

 

They could have put high viscosity oil in. It will make a difference in short trip driving and less so in high speed driving.

 

Oil should be 0W20 and not over filled. Tire pressure should be close to 40 PSI.

You'll need to find out what oil they used and the viscosity of that oil. Anything other than 0W20
will affect your MPG's. Always make sure the oil level is at the correct level on the dipstick.
They may have reduced the tire pressure too. Get a gauge and set it to 40 PSI and check it at least every month.

 

If you have the time and can afford it, you might consider doing a series of 'benchmark' runs at fixed, cruise control managed speeds, both directions, on a flat road, say 16 km long. Having a set of different mileage vs speed data points, we can then understand what is going on. Be sure to record the temperature on these runs as air density has an effect at higher speeds. The goal is to make a chart looking something like:


Bob Wilson

 

That's the wrong oil. You need 0W20 synthetic for your Prius. Change it ASAP.

 

Here's the data sheet for your car.

 

Toyota dealers aren't bound by Toyota. They're independently owned. Your dealer is a JERK.
Go to the auto parts store and buy the proper oil and filter and have an independent shop change your oil before you have possible engine damage..

 

Here's Toyota Lanka's fluids page. It shows 10W-30 regular oil and what looks like 5W-30 synthetic.

As DrD says, if you want 0W-20 you'll probably have to find an independent shop. Is this one near you?

 

People, relax. 0W20 is required in USA only due to CAFE regulations. Outside USA up to 20W50 is fine (depending on ambient temps).

Sumedha
What is your driving pattern?

 

Erm disagree with you there. It's 0w20 in all the major markets too.

I posted very early gen3 adverse mpg experience when my car was filled with 5w30. The dealers assumed the same oil as goes in the gen2 Prius would be fine in the gen3. Wrong. The mpg's dropped and getting over 50 mpg UK was very difficult and over 60 mpg UK was impossible. Performance at top end was also restricted slightly. Once 0w20 oil was used again the car almost instantly went back to the original high mpg's.

Not sure how hard 0w20 oil will be to source in Sri Lanka as it's quite rare here despite being required in the Toyota hybrids (Yaris, Auris, Prius) and many other Toyotas with start stop technology.

Maybe ship over 5 litres of Toyota 0w20 oil and change yours to it and see if mpg's increase. It's not cheap oil but it's a small price to pay for such a car.

 

There is a difference between recommended and required. There is no question that 0W20 will be best for fuel economy. I was the first one in this thread to suggest checking oil viscosity.

Related thread: Would you use 5W40 for your Prius C? | PriusChat

 

From my experience 5W-40 was responsible for at least 5% worse fuel economy (see my signature and records for 2011), 10W-40 in your warm climate should have comparable results.

A drop from 30 to 20-23 kpl is a little exaggerated to be a oil fault alone. Maybe it's the driving style or something else.

 

100% synthetic.