Your sludge buildup isn't caused by the oil.

Try switching brands or types if you prefer, but in the long run, you'll find your sludge is the result of something mechanical, not oil.

my engine doesn't have any sludge buildup at the moment. I'm just trying to look out for the long term of it so I can have as little problems as necessary.

Find me a car on this Forum that has sludge buildup caused by something other than an L36 UIM failure.

Sludge is not a common word here. 3800'* aren't prone to oil-related failures, sludge, or wear as long as oil changes are done on a regular basis.

Turn your attention to something other than sludge.

Aye, thats why I recommended switch intervals to every 3 months rather than 3000mi.
Do you think 6months would be ok? A year for Synthetic?

I run 5000 miles on the Zilla with synthetic.

3000 miles regardless of miles on the SLE with dino juice. That'* usually 4 months or so. Both engines are spotless.

I agree that the proper oil change intervals based upon what you use is more important than the type. Use the 3 month/3k miles for regular oil, and you may be able to push roughly twice that for synthetic, which is the main benefit of using synthetic.

If you want to worry about something with only driving that distance, worry about the exhaust system - but that'* another topic.