They way I understood it is-(I don't even pretend to be an oil student- Costco Chevron Supreme is fine for me- maybe the experts can decipher it all)
Mobil 1 is a Group III base w/ PAO's added. It is not a PAO base stock like true Group IV oils.
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Lube news reported Chevron displaying Group II and III base stocks to qualify as GF-4 w/ additives (as a benefit to vendors -economic advantage)
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By using Chevron’s all-hydroprocessed Group II base oil you can produce GF-4 quality lubricants with a simple one step blending process. Because they are all-hydroprocessed, our base oils have:
higher purity
better oxidation stability
higher VI
lower CCS viscosity
lower volatility
Consequently, no correction fluid is needed to meet GF-4 specs! Your additive supplier knows how to take advantage of Chevron's high-quality base stocks.
Blending Comparison: Meeting GF-4 Specs and (proposed) SM Specs
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I found this-but don't know if it's outdated-
ive been reading on other forums that mobil 1 is switching from group IV base oils to group III. for those of you who have no idea what this means...
Group II - Modern Conventional Base Oils
Base oils made by hydrocracking and isomerization technologies had such a signifigant increase in desirable performance over solvent refining technology that in 1993 the API categorized base oils by composition. Solvent refined oils are now referred to as group I base oils. Group II base oils are a vast improvement over group I because they contain lower levels of impurities. Because they are so pure, they have almost no color at all. Improved purity means the base oil and additives can last longer under use. The oil is more inert and forms less oxidation byproducts that can increase viscosity and react with additives.
Group III - Unconventional Base Oils
The API defines the difference between Group II and III base oils only in terms of V.I., viscosity index. Base oils with conventional V.I. (80-119) are Group II and base oils with an "unconventional" V.I. (120+) are Group III. Group III base oils are also called unconventional base oils (UCBO's) or very high V.I. (VHVI) base oils. Group II+ base oils have the same maximum V.I. as Group II (80-119), but have a higher minimum V.I. (110-119).
From a process standpoint, Group III oils are made by the same process as Group II oils, but the V.I. is increased by increasing the temperature of the hydrocracker. The product V.I. can also be increased by increasing the V.I. of the feedstock. Which is done by selecting the appropriate crude.
Group IV - Traditional "Synthetic" Base Oils (PAO)
"The word "synthetic" in the lube industry hase traditionaly been synonymous with PAO, poly-alfa-olefins, which are made from small molocules. The first commercial process for making PAO was pioneered by Gulf Oil in 1951. In the 1960's, Mobil patented an improved process. In the 1970's, Mobil began to market their product as 'Mobil 1'.
Since then, the demand for PAO has grown and some base oil manufactures began using higher V.I. feedstocks to make mineral oils with V.I.'s that matched the PAO's. These new Group III oils were not manufactured from small molecules like traditional synthetics but they bridged the performance gap at a lower cost. Some lubricant manufactures began replacing PAO's with Group III base oils in their "synthetic" engine oils. This created a controversy in the lubricants industry because some believed that PAO's were the only true synthetics.
The National Advertising Department of the Better Business Bureau ruled that Group III base oils can be considered "synthetic" because modern oils made using hydroisomerization technology have most of the same performance features of the early synthetics.
more info...
http://theoildrop.server101.com/forums/showflat.php?Cat=0&Number=749606&page=0&fpart=1&vc=1&nt=14
so yeah bummer. id like to keep using pure synthetic and wondered what other group IV synths people have been using. so far im leaning towards elf.ive been reading on other forums that mobil 1 is switching from group IV base oils to group III. for those of you who have no idea what this means...
Group II - Modern Conventional Base Oils
Base oils made by hydrocracking and isomerization technologies had such a signifigant increase in desirable performance over solvent refining technology that in 1993 the API categorized base oils by composition. Solvent refined oils are now referred to as group I base oils. Group II base oils are a vast improvement over group I because they contain lower levels of impurities. Because they are so pure, they have almost no color at all. Improved purity means the base oil and additives can last longer under use. The oil is more inert and forms less oxidation byproducts that can increase viscosity and react with additives.
Group III - Unconventional Base Oils
The API defines the difference between Group II and III base oils only in terms of V.I., viscosity index. Base oils with conventional V.I. (80-119) are Group II and base oils with an "unconventional" V.I. (120+) are Group III. Group III base oils are also called unconventional base oils (UCBO's) or very high V.I. (VHVI) base oils. Group II+ base oils have the same maximum V.I. as Group II (80-119), but have a higher minimum V.I. (110-119).
From a process standpoint, Group III oils are made by the same process as Group II oils, but the V.I. is increased by increasing the temperature of the hydrocracker. The product V.I. can also be increased by increasing the V.I. of the feedstock. Which is done by selecting the appropriate crude.
Group IV - Traditional "Synthetic" Base Oils (PAO)
"The word "synthetic" in the lube industry hase traditionaly been synonymous with PAO, poly-alfa-olefins, which are made from small molocules. The first commercial process for making PAO was pioneered by Gulf Oil in 1951. In the 1960's, Mobil patented an improved process. In the 1970's, Mobil began to market their product as 'Mobil 1'.
Since then, the demand for PAO has grown and some base oil manufactures began using higher V.I. feedstocks to make mineral oils with V.I.'s that matched the PAO's. These new Group III oils were not manufactured from small molecules like traditional synthetics but they bridged the performance gap at a lower cost. Some lubricant manufactures began replacing PAO's with Group III base oils in their "synthetic" engine oils. This created a controversy in the lubricants industry because some believed that PAO's were the only true synthetics.
The National Advertising Department of the Better Business Bureau ruled that Group III base oils can be considered "synthetic" because modern oils made using hydroisomerization technology have most of the same performance features of the early synthetics.
more info...
http://theoildrop.server101.com/forums/showflat.php?Cat=0&Number=749606&page=0&fpart=1&vc=1&nt=14
so yeah bummer. id like to keep using pure synthetic and wondered what other group IV synths people have been using. so far im leaning towards elf.
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http://en.wikipedia.org/wiki/Lubricant
http://www.texasoffroad.net/forum_php/showflat.php?Cat=&Board=Amsoil&Number=152529&Main=147556