I had not thought of VVT. Good point!

Even stuff like STP is suspect with the VVT.

GM says don't use any additives, but the dealership sells the expensive stuff. Before they got caught they were selling power steering flushes.

GM even has TSBs against additives and flushes that are routinely offered by Service Departments. That leads me to believe that they are useless.

You know I didn't think of vvt either which I have in my 2.4. Apparently it causes a chemical reaction in rubber only and gives the Rubber elasticity without making it soft or harming it's integrity. It doesn't do what the others do apparently and is meant as a one time use. It's got a pretty good reputation I just am curious exactly how it works. Also, it just mixes with the oil and doesn't react with or bond to it. When it flows past rubber with the oil it reacts with the rubber it contacts. Some people even spray the stuff onto bushings and other rubber suspension stuff. Interesting! I know the other thick additive gum up and overswell gaskets and make a mess of the oil pan but this stuff according to reviews just works without any of those side effects somehow.

and since the stuff doesn't thicken the oil more change viscosity properties the risk of harm to the vvt system would be a non issue. I think the additive that change how the oil acts inside the engine would, and that's probably what was in the tsb.

Polyethelene glycol is Miralax.

Glycol ethers are a group of solvents based on alkyl ethers of ethylene glycol or propylene glycol commonly used in paints and cleaners. These solvents typically have a higher boiling point, together with the favorable solvent properties of lower-molecular weight ethers and alcohols.

I don't understand lol 😂

Banana peels and all work good too.