oil type and fuel economy

Check the oil level.. DO NOT OVERFILL..If you overfill it will hurt your MPG's

 

The short answer is that little difference is seen between oil changes by most PC members. The variation in gas pump shutoff point has usually been the biggest factor. While most of the things you said were unchanged, this one can cause a short term effect. No significant mileage differences have shown up between syn and conventional oil over quite a few threads.

 

It's your turn to entertain the evil spirits.

 

Pennzoil dino oil...that stuff is crap...makes me shudder...

Why don't you put in Mobil 1 and change every 10,000 miles. Lot less used oil. Some people go 15,000 no problem.

 

Just put in Mobil 0W30 and the car is very quiet. Checking the MPG with the AC off this week. Man it is freaking hot. Any test results on 0w30 and 0w20 and 5w30?

 

I'm at about 3500 on the odometer (had the car since March) and I'm thinking about changing to a synthetic - either Amsoil or Royal Purple. Then I'll probably keep my interval at about 5000 miles, which should work out to twice a year for me.

As said, be VERY careful about the level. It's been observed that overfilling can cause issues. Better to fill with a bit less than the recommended, drive until warm, then check the oil level and bring it up as needed.

 

I use Mobil 1 0W-20 and get a 2-3 mpg boost vs. a dino 5W-30. I still change every 5000 though could probably go 7500 to 10000 safely.

 

May try that next oil change. Has Toyota officially allowed 0W20 for 2009 models?

 

Another post a few months ago restated that 5W-30 is the correct oil for the Prius

 

Yep! In addition I read several other posts that said Japan and other places use 0W20 and that the 2010 does in the US and that Toyota was changing their policy for the US. Just curious if that ever happened! I am using 0W30 in all my Hybrids and regular cars with great results so far. But then again I change my oil oil every 3K. Dirty oil just does not make me happy folks! So I could be waisting my money on synthetic oil! However 0W30 only comes in synthetic and I have seen the difference in MPG and performance with 0W30 over 10W30 and 5W30. 0W20 is required for my Honda but my engine makes less noise with 0W30. 0W20 is a little thin for hot climates! IMHO

 

My gas mileage with an 08 prius had been consistently 47 - 48 mpg around town; I never exceeded 50 mpg. A month or so ago, I (self) changed to mobil1 0w30 "energy saving" oil from the dealer's 5w30 and immediately saw a 5 mpg boost. I ran half a tank on my usual daily commute before the change (48 mpg average), after the change (same tank of gas, same route etc) I saw 53 mpg. Since then I've been very consistently getting mid 50's mpg.

Mobil claims you will see a 5% boost in fuel economy - I am doing much better than that. I've already picked up another 5 qt jug ($23 at Walmart) to take advantage of the mobil $10 rebate (max two per address). $2.60 a quart for full synthetic is a great deal.

 

Yes, I agree that this mpg gain is reasonable with 0W-20.

No. Also, note that my 2004's oil consumption (with 81K miles now) increased markedly when using 0W-20 during the winter months in southern CA. More than one quart over 6,500 miles. I switched back to 5W-30 for the summer and don't plan to use 0W-20 again.

 

Though it's not surprising that 0W-20 would yield slightly higher mileage, I'm pretty sure it is not on the recommended list for U.S. Prius' (Gen 2). So I would not risk my warranty for 2 mpg. Separately, frequent oil changes to not mitigate the risks posed by low viscosity. I really would not use oil that is out of spec for the car - especially during the warranty period.

 

0W30 works on all my vehicles and it is not worth the risk to use 0W20 in a hot climate. I noticed more engine noise in my Honda years ago and quit using it because of that. However, you guys in the great white North are all over this in the winter.

 

In Europe, 0W30 synthetic is recommended and we change it every 15000 km (a bit less than 10000 miles) or once per year.

 

Ok, so at the risk of sounding dumb.....my next oil change what should I use?
I have a 2007 Prius with around 51,000 miles on it. I live outside of Buffalo NY, but will be driving down to my other home in central Florida in October for a month, then again in April for a month, but being up here in western NY for the other 10 months, during both summer and winter.

It seems the common sense compromise is to use synthetic 5w-30....not risking the 0w-30 because of those two Florida months.

Is it the 0w that gives you the better mileage or the synthetic aspect of the oil?

The 0w-30 sounds enticing, but perhaps I'd better stick with the 5w-30. In the past I was always afraid to change from dino to synthetic in a "used" engine, but I think I'd do it with the Prius.

All my past cars have been non-hybrid cars, and I also used Auto-RX in them. Has anyone ever used it in their Prius's ??

Frank D.

 

post not needed

 

My opinion about oil FWIW - higher gas mileage = less wasted effort by the engine.

The most obvious improvements are better tires (lower rolling resistance), lower weight, and better driving technique. Once those are exhausted you can reduce internal engine friction.

If you see higher mpg you have lower friction. Lower friction = lower engine wear = good! Clearly that is an oversimplification because increased engine wear could occur for a few minutes after startup or for a short period during extreme driving conditions and be masked by longer periods of low friction. However this seems extremely unlikely to occur with 0W-30 synthetic (imho). Remember: the "0W" part refers to the low temperature viscosity - the "30" is the high T value. I live in Mississippi so I don't encounter low T's very often and the high-T value meets Toyota specs (Mobil claims 0W-30 is a straight replacement for 5W-30 and it should certainly be so for me). I won't use a 20-weight high T oil - that seems to me to be pushing things.

 

I would also enjoy an answer to this question.

I have a 2007 as well that is coming up on 60,000. I've used synthetic 5w-30 mobil1 for all but 2 oil changes at 5,000 mile increments.

I've lived in NY for 40,000 of those miles, Boston for the other 20,000.

I thought I knew what I was doing until I read this thread.