Originally Posted By: Garak
That, in a nutshell, is the biggest problem. Assuming that two or three different reputable oils of your choosing actually meet the specifications you need or are searching for, then how are you really going to differentiate between the two or three?
That's one reason I can't justify spending more than $5/quart. For 98% of road applications I can't see how any extra benefit you might get from a more expensive oil is likely to make any difference for as long as you'll have the car when you're comparing the top spec oils (i.e. A5, Dexos1, etc.).
But some caution is advised as there are some bad oils out there. PQIA has tested at least a dozen different oils that could easily harm engines. They're all off brands and don't have licensed certifications. Some flat out lie on their labels as to what they are and might not even be suitable for your lawnmower.
Here's an oil the manufacture claims is made from "high grade base stocks" and offers the "finest protection". They mention it's suitable for "all foreign and domestic cars" and list SF, SG/CC, SH, SJ/CD on the label. But, in reality, it's only an SA/SC oil and the grade isn't even correct. See:
http://www.pqiamerica.com/November 2011 samples/MaxiGuard.htm
I also discovered all the big oil companies
sell millions of gallons of line wash to some of the smaller lubricant companies. It's what comes out of their pipes and tanks when they switch from one product to another. It can have gear oil or ATF mixed with motor oil. It's supposed to be used for stuff like chain saw bar oil. But it's been discovered a lot of it is ending up being sold as motor oil by less than honest smaller companies.
So I'm suspicious of the unlicensed and uncertified oils and manufacture's claims. Obviously there are some companies more interested in maximizing their profit rather than producing a reputable product that will properly protect your engine. Plus uncertified oils (or the wrong certifications) invalidate car warranties. Some of these uncertified products are marketed as being more "green".
I've also noticed, as I'm sure others have, the big brands seem to compete on price when all else fails. They're obviously trying to lure people into switching oils. During one trip to the store Mobil 1 EP is $29 for a 5 qt jug and Valvoline Synpower is $22. The next time I'm there the M1 is $23/jug and the Synpower is higher. Sometimes the name brands of full synthetic are even priced under the store/off brands.
If I lived in a warm climate and mostly drove longer distances I'd probably just use a name brand conventional oil and I don't think it matters much which one as long as it meets the spec for the car (i.e. GF4, etc.). The PQIA and IOM tests back this up. Even the cheapest GF4/5 oils from Shell, Chevron, Castrol, Pennzoil, Mobil, Quaker State, etc. are all within 10% or 20% of each other in nearly every single test. See:
http://www.pqiamerica.com/testresultssep2011.html
and also:
http://www.pqiamerica.com/testresultssep2011page2.html
I live in a colder climate, often drive shorter distances, and am interested in extended oil change intervals. So for me personally it's worth spending $2 more per quart and getting a $25/jug name brand full synthetic that's certified to the Euro A5 standard for extended drain usage. It might be safer to run longer and it will flow much better for each cold start compared to a conventional GF5. And of the A5 synthetics, I like the test results of Valvoline Synpower and Pennzoil Platinum the best for my needs.
So I've learned a lot and perhaps my posts will prove useful to at least a few others here. Thanks for the helpful contributions.