On my 4runner i used Valvoline conventional motor oil for the first 5000 miles, and i cahnged it 3 times in that interval.
Then 5000mi oil changes with fully synthetic after that. Almost 100k miles and it runs perfect.
I'm thinking to do the same with this van, especially since GM recommends 5w30 for this engine.
I will brake it in nice and slow, but that cannot offset bad engineering ...
We'll see.

what reports have you heard regarding the cause of the oil consumption?

its your truck so do what you want. 5000miles is a long time. Imo you shouldn't extend the interval even with synthetic oil. Oil must do 3 things, synthetics don't help with all of them. If a shop does your fluid changes...get a sample at 5000miles...its black as tar.
if you meet any of the severe driving conditions 3 to 4000miles is a better interval.

Quoting from one of the articles I found:https://chevytrucks.org/gm-6-6l-l8t-engine-guide/

6.6L L8T Common Problems

• Excessive oil consumption
  
• Exhaust manifold leaks
  
• Knock sensor failure
  
• Timing chain issues
  

1) Oil consumption

One of the most common problems with the GM L8T engine is its high oil consumption. Many owners have reported that their engines consume up to a quart of oil per 1000 miles.

Excessive oil consumption actually affects a lot of different engines and is common amongst direct injected vehicles. On the L8T it is thought that either the piston rings or the PCV valve are the causes of it. Regardless, we haven’t really seen many issues associated with this when properly taken care of.

Excessive oil consumption can become a bigger problem if you allow your truck to run on low oil levels. We always recommend keeping a few quarts in the truck so that you can fill-up as needed if you get a low oil light during a trip.

A technical service bulletin has been released for this noting that high oil consumption typically occurs while towing heavy loads.

beauty

Motor Oil:

1. It lubricates the parts.

2. It cools down and transfers heat from many parts.

3. it is used to pressurize certain parts such as hydraulic lifters.

I disagree with you when it comes to oil changes on an engine that is completely broken in.

I use 5000 miles as my oil change limit, as I use synthetics. If I used conventional motor oil then 3000
miles would be the limit. I don't care what the oil change monitor says. I grew up without such devices,
and have no need for them. I'd rather have an oil pressure gauge on my Malibu, than that piece of junk. My Bu's motor oil is not black when 5000 miles go by and she is at 96,000 miles now.

oil carriers particles in suspension and it has it limit as to what it can carry. Filters aren't 100% efficient. the new tech with small filter screens. If you are not having issues continue as is. Its what i see daily in repairs; oil changes are cheap insurance.

I started this thread to ask OWNER FEEDBACK about some concerns I have re: oil consumption with the 6.6L gasoline engine.
I found on the net and youtube that quite a few owners complain about oil consumption.
So i thought I would ask those people who own this engine, if they experiece this issue or not.

I don't want this to turn into an "what oil" and "what oil change interval" discussion, and opinion debate.

Thank you to those who provided good info and encouragement.

@KubiJ1AS did you receive your van? I have called all over North Texas and every dealer says they can not order an express van with a V8.

Dealer called a couple weeks ago and said the order is going in, Should be ready for delivery in a couple of months or so ...

This is the only dealer in my area that actually took an order, all other Chevy delaers say they cannot put any orders in...
Not sure what's going on. I'll belive it when I see it ...

I found one out of state and went and bought it. I’ll post back about oil usage. Alignment was off with only 4 miles on it when I drove off :/ Hoping just something minor.