Ok so I was getting between 38-39 mpg right befor I had my first oil change and now I'm getting 36 mpg on the first tankful since the change..This doesnt make sense!! Its warmer and I'm having trouble driving hybrid. What possibly could be wrong??

 

Check to see what weight oil was used. It should have been 0w20 or 5w20.

 

Total BS, We have never run anything but 10-30 full synthetic and running 42-43 averages, in fack last tank was 48.5. Every one seems to be a big lube engineer, free advice is just that free and not worth the powder lol!!!

 

Skywagon: Check your owners manual and after that tell Toyota that they need to check with you before stating the proper oil for the TCH in the owners manual.

 

Your'e wrong on this one Skywagon. I don't know where 'Sootville' is, and your profile doesn't say, but in colder climates the oil does matter. Actually it matters everywhere -- just to a lesser degree in warmer areas. The factory manual says 0W-20 or 5W-20. I don't know all of Toyota's reasons, but here are a few of my own based on carefully kept performance logs and the conclusions taken from them.

• The TCH, like all Hybrids starts and stops its engine a lot, and higher viscosity requires more current to turn the engine on each start because the resistance is higher.
• Due to the pumpless splash lubrication for the PSD, the oil fling (sling?) to the various lubrication cavities is based on engineered values using the factory recommended oil. Higher viscosity oil, when cold may not distribute as well because it will be 'stickier' and not fling as well.
• Similarly, when coasting or in EV mode in cold weather or with a cold engine the drive train resistance will be slightly higher with higher viscosity oil.
• Finally, the ability of an oil to transfer heat is related to its viscosity. An oil with a viscosity higher than the engineered lubricant may sheer and fail to provide efficient heat transfer at the lower temperatures that result from a hybrid operating more frequently with its ICE off. This could shorten the bearing life of the drive train, if not the ICE bearings themselves.

Incidently, on the last point, synthetic oils like Mobile 1 are usually superior to the pure petroleoum based ones. This is the primary observable difference between the two.

 

I agree with the other posts that the weight of the oil is important. Another issue to consider is how full the engine is filled with oil. I noticed that my oil was right at the full mark when I received my car. Some places tend to overfill which can adversely affect mileage. This can happen even at Toyota dealerships.

 

Perhaps the place that changed your oil also let air out of your tires as a service to you at no extra charge. Some places claim to inspect and top off fluids and air etc.

Low pressure in my tires is the first thing I check. The only OTHER thing that has impacted the mpg in both my cars is the new ethanol fuels that started a month ago here. Maybe in your area too.

Check it out!

Tony

 

Try making a longer trip with the A/C off. The warmer weather means your A/C is running. The ECO button does a nice job of keeping your MPG up...


BIll

 

The oil change etc was done by my Toyota dealer. So I'm assuming they put in the correct oil. Bill only says Mobil oil. Also they rotated and balanced tires. I did the recommeneded first service check. Perhaps I will call them tomorrow and ask what oil and what pressure. But I cannot undo what they did right? Thanks .........................

 

Get a tire gauge for a few bucks and measure the tire pressure. If you have the pressure which is recommended by the manufacturer you will most likely be getting less mpg than are possible.

On the side of the tire is information indicating MAX tire pressure for the particular tire you have. You can safely go up to the max pressure but not above.

So, if for example, your current pressure is 32 and the max pressure on the tire sidewall is say 48 you could increase the pressure to somewhere in between and see how that does for you.

Tire pressure on my two cars seems to be the biggest contributing factor to mpg in my experience.

Be sure to take pressure readings when the tires are cool, meaning not driven very far. Pressure will increase a couple psi when warm and lose a couple as well when cool.

Good luck