For the oil experts on here. I know there has been extenive talk on which oil to use and there are many varying opinions. My question is on the use of multi weight oil. In hot weather (Florida) is it necessary to run a multi weight oil or can I use a straight weight (40) oil. I've been using 10w-30 VR1 and had it tested at Blackstone. It came back rated at on the low side of 30 weight on the viscosity.
Oil viscosities
- Thread starter Bandit395
- Start date
This is an interesting link, with some good information, but hardly a bible. I would figure that "bible" implies inspired by God and penned by a prophet meaning the info should be infallible. There are numerous statements in this “bible” that are clearly wrong and I certainly don’t have the time to fret them out nor is there a pressing need to. That said I will take a minute to point out a couple things that are not exactly correct.
First, there is misinformation regarding synthetic oils, the "bible" says:
"Despite their name, most synthetic derived motor oils (i.e., Mobil 1, Castrol Formula RS etc ) are actually derived from mineral oils - they are mostly Polyalphaolifins and these come from the purest part of the mineral oil refraction process, the gas," and then he follows with "Pure synthetic oils (polyalkyleneglycol)..."
These statements lead the reader to falsely believe that PAO oil is not real synthetic but PAG is.
The difference between mineral and synthetic oil is in the actual molecular makeup of the oil, specifically, the molecules that make up synthetic oil are not found in the mineral oil feedstock from which it is synthesized. This generally accepted definition applies equally to PAO, PAG, and many other truly synthetic oil base stocks.
One of several raw feed stocks for PAO production is ethylene gas from mineral oil production; however, PAO has no free ethylene in it. The PAO is synthesized from the ethylene.
One of the raw feed stocks for PAG production is ethylene oxide, which itself is made from ethylene. There is no free ethylene oxide in PAG. The PAG is synthesized from ethylene oxide which is made from ethylene.
Ethylene is one of the most versatile feed stock chemicals in a petrochemical toolbox, and is used in the manufacture of HUGE number of different plastics, antifreeze, oils of many types, cosmetics and many more.
Second point of confusion:
When describing viscosity, the "bible" does not delineate between the two different numbers in a multi-viscosity API rating. The API rating system relies on standard ASTM tests to determine the suitability of an oil for different temperature operation ranges.
The first number in an API multi-viscosity rated oil (e.g., the 10W in a 10W-30 oil) is merely one of 6 "bins" between 0W and 25W. The rating is established by the coldest test that an oil successfully passes in the D4684 Pumpability and D5293 CCS tests. The viscosity is measured in these tests using different types of rotary viscometers, and this viscosity is used as control point in the measurement, but it does not become the viscosity rating. In other words, this "W" viscosity does not correlate to an actual measured viscosity as does the second number in the rating.
The second number in a multi-viscosity rated oil is measured using a standard ASTM D445 measurement, with the additional requirement that it pass a D4683 High-Shear test with a minimum viscosity.
Oils of similar API viscosity ratings vary widely in many characteristics, especially at the lowest parts of their operating temperature range. The API viscosity rating system is merely a way to classify oils of similar viscosity characteristics.
The API rating does not predict flash or boiling point of oils that pass the D4683 test at high temperatures, nor will it predict the clouding or gelling point in oils that pass the "0W" D4684 and D5293 low temperature tests.
