New style VS old style PCV?

[Rayyy]

Ok, here is another very informative thread comparing the differences between the old version and then new version valve covers.

It looks like the new version does have a few additional design changes to help it drain the oil and prevent it from spitting out through the PCV.

https://bobistheoilguy.com/forums/threads/gm-ls-engine-3rd-revision-valve-cover-install.251305/

 

[Rayyy]

Yes, it requires drilling and a little dremel work to get the right diameter for a grommet to fit. Then get a grommet and pcv for a 02 and prior setup.
Or go to the junkyard and just grab one from a 2002 or earlier vehicle. Ive done it both ways, and use them on my 06 Tahoe and Silverado. Just open up the drain holes in the baffle, they are TINY and plug with carbon. Then the oil goes through the pcv ( either style) and into the intake.
When i worked at the gm dealer we did this often and had zero returns for oil consumption or smoke.

So, using the older style (removable PCV valve) valve covers and opening up the drain holes is better than using the updated valve covers with the built-in orifice?? Even if opening up the small drain hole as well?

I also read on another site that drilling out the drain holes can cause oil pressure fluctuations... Does that even make sense?

 

[Mudsport96]

So, using the older style (removable PCV valve) valve covers and opening up the drain holes is better than using the updated valve covers with the built-in orifice?? Even if opening up the small drain hole as well?

I also read on another site that drilling out the drain holes can cause oil pressure fluctuations... Does that even make sense?

Not sure how opening a non-pressurized drain could possibly cause oil pressure fluctuations so i wouldn't worry about that.
As for older pcv with opened drains vs newer orifice with opened drains. I can't elaborate as i have an original pcv valve cover and a newer that i converted to pcv. So both run the old style pcv and have no issues. And in the last year i also added an oil catch can to both vehicles. The Tahoe averages about 2 ounces per oil change and the Silverado about 10 ounces per oil change. But it also has over 400k on the engine so blow by is expected.