My oil choice for 2010 Prius

My Package V Prius has 1078 miles so far and I started thinking about what oil to use when the times comes to change it should be. I choose Honda 0W-20.


I live in the NE USA and most of my driving is short trips with a few medium trips thrown in. Extremely little high speed highway driving. I bought the Prius for it's great gas milage and the recommended weight of 0W-20 fits in well with my goals and driving style. As a side note I switched my 2007 Prius to 0W-20 before it was sadly totaled by hitting a dear.


From used oil analyses that I've seen, the factory oil fill in the 2010 Prius has loads of molybdenum. It is unclear if this molybdenum is from the oil, assembly grease or a combination. However, Toyota has it in and both Toyota 0W-20 oil and Honda 0W-20 oil have a sizable molybdenum content in the oil from the various virgin oil analyses I've seen as well.


Mobil 1 makes a widely available 0W-20, but it has no molybdenum and I've been less than sanguine about Mobil 1 since the flap with Mobil 1 5W-30 failing the ASTM Seq. IVA valvetrain wear test.


Amsoil makes a great 0W-20, but it's viscosity is at the high end of 20 weight oils and I want something thinner. I used this in my 2007 prius because it was thicker than any other 20 weight that I've found.


Redline makes a very interesting 0W-20, and it is one of the few besides Honda and Toyota that has molybdenum in it. I would have used it except that it has a very high level of ZDDP (above even that which is found in older SL rated oils) which while great for reducing engine wear can, over time, poison the catalytic converter shortening it's life. I want good wear protection without trading off against catalytic converter life


Penzoil Platinum makes a 0W-20, but I do not know about it besides a nice low viscosity. If this oil becomes more widely available I may use it in the future.


Eneos makes a 0W-20 and rumor has it that it is the source of Toyota's 0W-20, but I do not know if that is true or much about the oil.


For now I will be using Honda 0W-20 and Toyota 0W-20 oil for my Prius.


Rumple

 

The hot (non-W) number specifies a range of viscosities for the oil. The manufacturer is free to place the oil anywhere in that range. For example, high mileage oils are generally thicker than their non-high mileage counterparts.

Another example looking at two 0W-20 oils. Here is the product data sheet for Pennzoil 0W-20 oil (click on the "product data sheet icon). You can see that it's 100C viscosity is 8.39cSt while Amsoil 0W-20 has a 100C viscosity of 9.0cSt. Amsoil 0W-20 has the highest viscosity of any 20 weight that I've managed to find.

The ranges of viscosities specified for a 20 weight oil at 100C is defined to be more than 5.6cSt and less than 9.3cSt. (see here for the full details ). Most 20 weight oils seem to be in the 8.0cSt - 9.0cSt range.

Rumple

 

You are right about M1 having some non-trivial amounts of moly, and as you point out it is only around 10% or so of the amount that the Toyota/Honda/Redline have.

The two unique characteristics of the Toyota 0W-20 oil is it's high moly and it's high viscosity index (VI). The high VI may help in mitigating the rough start issues that some people occasionally have, especially if the issue is in the oil driven variable valve intake system control (VVT-i). This is pure speculation.

The bottom line is that *any* 0W-20 that meets SM/GF-4 (or now the new SN oils coming out) will work fine for the most part. Fretting about oil choice is playing on the margins and might make some small difference in some cases, but only worry about it if you like to worry about oils (which I do!)

Rumple

 

Slight terminology issue - mineral oil is petroleum base. See [ame="http://en.wikipedia.org/wiki/Mineral_oil"]here[/ame] for this quote "In today's petroleum exploration and production (E&P) business, the phrase "mineral oil" is most often used in legal documents to define and encompass all of the liquid hydrocarbon and gaseous products produced from wells drilled into underground petroleum-bearing reservoirs".

What you are thinking of is the group of the oil (I, II, III, IV or V). The first widely marketed to consumers, and still many of the finest, synthetic oils are group IV oils or polyalpha-olefins (PAO) oils. Group V oils are esters. Group III oils are also marketed as synthetics in the USA and are extremely refined and modified petroleum oil rather than being synthesized from smaller molecules such as group IV and group V synthetics. They perform extremely well and similar to the group IV and V oils.

Some people like to run oils with more group IV or V base oils rather than group III. It is very difficult to get the base oil breakdowns of oils as most manufacturers do not tell you, so it is a bit like tea leaf reading. Over at bobistheoilguy.com you can Google to see the various opinions as to what oils are made with what bases.

Rumple