Think the issue is not here. Different claims of oil manufacturers and answers of many oil lab specialists could not fully convince me that hyrdocracked oil may be really equal to synthetic oil or even outperfom them in certain areas. But the tests made by a chemist from Melbourne finally did it:
http://www.exclusive-auto.net/articles/general/engineoiltest.html
Elf Excellium LDX 5W-40 and Agip Sint 2000 10W-40 that are mainly HC oils with some 20-30 % share of PAO showed considerably better performance then some pure synthetic oils. No a prejudice against HC oils now !
The main issue (and I am not confortable with it ) is that changing their oil compositions manufacturers try to pass over in silence what they have changed and whether the performance of these new oils are really better then that of old ones.
After reading Melbourne tests I decided to do my home work on 0W-40 leader and find out what ELF Excellium 0W-40 we are offered now. The results confirmed my apprehensions:
..................... 2002 ......... 2003
Density .......... 0.861 ....... 0.847
Viscosity 40C ...... 79 ........... 75
Viscosity 100C ..... 14 ........... 13
Flash Point ........ 240 .......... 232
Pour Point ........ - 51 ......... - 42
Could Melbourne tests be valid now ?
Mobil or Elf are not alone where properties like Flash & Pour Points, NOACK volatility became worse. Products from Motul, 76 Unocal, Comma (Mobil) and many other manufacturers experienced the same changes, but no one has openly said to end-users about these changes. No doubts their properties remained within API ot ACEA requirements, but it is not enough to know. Think it should be some law to make oil manufacturers publish all product data and promptly inform end-users about changes. Then we shall be able to make our choice with open eyes.