Originally Posted By: ZeeOSix
I don't think the ISO 4548-12 test spec specifically says you have to express your data with the '@' symbol. This has been beat to death a few times, and for all practical purposes when talking about filter efficiency, the '>' is essentially the same as '@' when you approach the stated particle size. In other words, 20.000001 is still > than 20 ... so it's basically becomes '@20 microns'.
At least Fram specifies that their efficiency numbers are based on the average of 3 or 4 different sized filters, unlike Purolator, etc who always use their most gigantic filter as their test reference.
The ISO does use @ and that is important because there is the margin of error (+/-) that goes into the use of @ for the standard. However, the ">" approaching 20.000001 is not what the testing standard describes (nor what it is testing) so we are at a loss due to Fram ambiguity. It is really 98.8 @ 20? We don't know. Normally, when I see ">" within research, it often (but not always) includes a accumulation within a range. So, Fram using ">" when others are using "@" is just as big of an issue as when Wix is mum on the standard and everyone else is citing ISO 4548-12
Another substitute example. Volatility @ 250ºC (ASTM D5800) is capped at 15% for the SN standard, yes? That standard also uses the "@" symbol. So if Brand X is 14% @ 250ºC (but does not specify ASTM D5800)and another (using the "" symbol, lesser than for this example) is 13% " user changes what the standard is using, it becomes muddled. So which is best? We can't make a apples to apples comparison. It is not that Fram is a "bad product" just using less that optimal marketing language. I still think that the Ultra > XP.
It is marketing muddling to hopefully have a user make a faith-based decision.
I think we both agree that Purolator is ummmm..... tearrific.
