Anyone know which Xw30 has the highest Noack? Or for that matter I might consider an Xw40. I'm sure that Amsoil, RLI, and Redline will be mentioned and considered. I'm looking for something that can be had at the typical auto parts store or even WalMart. I have a gasoline direct injection application and of course the pcv gasses wind up in the intake tract. I fear that eventually there will be deposits on the backside of the intake valves from any "burned off" oil that arrives there via the pcv. Of course with DFI there is no fuel to wash off the back of the valves as in a "normal" FI engine. I would modify the pcv to vent to atmospheric but there are environmental and warranty issues to be considered. The other concern would be oil seepage past the valve guides that cooks on the valves. So an oil that leaves little residue may be more important than Noack. Then there are reversion gasses to be considered. Pontiac requires a 4718M oil for the LNF engine which I believe has a slightly lower than GF4 Noack among other things. Maybe I should just stick with the spec oil and trust GM on this one. After all unlike Porsche's and some others DFI there are no reported problems with intake valve deposits with this engine....yet. 2007 Pontiac Solstice GXP 0-60 4.6 / 1/4 13.26 @ 104 Rickey.