0w-30 oil

It is a good oil. Probably better than Mobil 1 5W30. However, many ill informed people will think it is "too thin". It should not void any warranty requirements.

It will be a bit thinner at startup than the 5W30. (Which is a good thing) At operating temps it will be a tad thicker than M1 5W30. (Which is just fine) Since it is thinner at startup, they claim that it saves gas. Not because it has some "added lubricant."

 

If I may, oils are manufactured such that they have a certain viscosity at two temperatures - 40*C and 100*C.

M-1 0w-30 viscosities are:
cSt @ 40ºC 63.1
cSt @ 100ºC 11.0

M1 5w-30 viscosities are:
cSt @ 40º C 64.8
cSt @ 100º C 11.3


By contrast:

M1 10w-30 viscosities are:
cSt @ 40º C 62
cSt @ 100º C 10.0

These viscosities are taken from the M1 website.

The relative viscosities can sometimes be surprising. Not at all what you think they might, or should, be.

To further contrast, the two least viscous easily found 5w-30's I'm aware of are Castrol Syntec and Havoline Deposit Shield. The last known numbers I have are:

Castrol Syntec
cSt @ 40º C 58.2
cSt @ 100º C 9.7

Havoline DS
cSt @ 40º C 59.4
cSt @ 100º C 9.7


Whether any of these oils are more than a hard spit apart in performance or price is questionable and probably mostly marketing hype. I'm all for reasonable oil change intervals more than finding "the most perfect oil in the world." Though it is understood we all have our little pecadillos when it comes to oil...

 

I have used M1 0w30 twice, usually I use Castrol Syntec 5w30. The first time I used it I didn't really see much difference, but my wife was using the car more then. The next time I changed the store was sold out so I switched back to Syntec. The wife quit needing to use the Prius and my tanks were staying at about 59 - 61. This last time I changed oil I went back to the M1 0w30 and ever since I have consistently held around 62 -64 MPG (normal driving 50 % highway). I say overall it may improve your MPG by 1 - 3 MPG.

 

I am using Mobil 0W-30 full synthetic oil, and so far its been great. My MPG's have gone up, but I don't really know if it was anything to do with the oil or not ..

 

If you're envious of those high mileage figures you need to live in a flat state to make it easier to achieve. I am in California also, but I notice that when I run a reasonable speed over a flat course, I have no trouble getting mileage in the high 50's or better. Mileage on the flat at about 40mph w/cruise gets easily >60mpg. Throw in just a few hills and it drops back to low 50's and with short trips high 40's. I've had my car about 3 months and do try to P&G and watch the high speeds, combination highway and city I can do low 50's pretty easily.

 

I changed to the Mobil1 0-30 at 3500 miles and have easily averaged 56+ MPG since. Don't really know how much influence the oil has, but must be a positive one anyway.

 

yeah we have 10 % ethanol in our gas here too. Ohio isn't necessarily flat but has lots of long hills that don't really kill your mileage while going up, but are steep enough on the way down that you can easily maintain a glide without losing any speed for long distances. Even in the dead of winter here last year I think my worst tank has been 46 MPG.

 

With my oil change last month I switched to the Mobil 1 0w-30 oil.

It was kind of like a "what the hell, why not" decision to try it. I'm actually skeptical as to whether it will produce measurably better mpg than the Mobil 1 5w-30.

 

I use 0W oils at the very least, in winter, due to superior cold temp pumping performance. Those who don't live in bitter cold winter climates probably won't have much to gain

The SAE covers all of this in their J300 spec, which calls for a maximum cold start pumping viscosity of 60,000 centiPoise. It has been empiracally determined that this is the yield stress point of a motor oil, at or beyond which the oil ceases to flow

A 0W oil must have a maximum cold pumping viscosity of 60,000 centiPoises (60,000 cP or 600 P) at -40 C. A 5W oil can reach the 60,000 cP max at -30 C, although the spec was recently moved to -35 C

According to Mobil 1 specs, their 0W-30 is rated 11,100 cP at -40 C. Their 0W-20 is rated 5,642 cP at -40 C. A conventional 5W-30 may rate as high as 78,000 cP at -40 C. Clearly, the 0W-30 and especially the 0W-20, offer far superior cold temp performance

Again, if your normal winter temps never drop below -20 C, you probably have little to worry about

 

As Jayman pointed out, there is more to an oils viscosity than the 40C and 100C viscosities. At colder temps the oil starts behaving differently. It is at those colder temps that the 0W oils show improvement in pumpability over the 5W oils. Whether you have to have temps below -20C or 0C or 10C to realize benefits of a 0W oil is another argument.