I know this is an old thread, but I'd like to give some feedback from personal experience.
First of all, nearly all VVT engines are extremely sensitive to anything other than manufacturer recommended oils. I know this from experience. Subaru engines are probably the most sensitive. I have a 2013 Scion FR-S with 139,xxx miles that now needs the VVT system replaced due to adding/running 1 quart of 10W30 between oil changes. I had a little bit of what I thought was a lifter tap. It was the vacuum pump that was making noise. Apparently the 2.0 AT Boxers have those and they just start rattling making you think it's a lifter.
The reason I'm making this comment is because of my current situation.
'99 Ford Explorer 4.0 SOHC with 114,xxx miles. I blew a head gasket and cracked a head. Pulled the heads, then parked the truck for a little over 3 years. Finally got around to fixing it. Bought 2 used engines for $200 and used 1 head and other miscellaneous parts. I did a timing job while it was out. Replaced everything from the block up.
Well, long story short.. I finally got it done, installed, and fired up. It ran like crap. Turned out the mud daubers plugged the fuel line running to the passenger side fuel rail, so I replaced it. It went from running on 3 cylinders (only driver's side) to all 6, but cylinder 1 wasn't firing good. I changed the plugs again, wires, coil pack, etc. Did a compression test and that cylinder was low. Only 92 psi. Frustrated, I added a bottle of Restore to it and within 20 minutes of driving, the engine started leveling out. I'm thinking it has a bad compression ring or maybe a stuck ring. Idk. I'm going to run it more tonight (10/21/2020) and I'll test the pressure tomorrow morning and get back with the short-term results.