My 2006 Hummer H2 has 135,000 miles on it. I normally use Valvoline 5-30 conventional for my oil changes. I have heard with an older motor that switching to a synthetic could be beneficial. Has anyone been in this situation and have any advice for me??

 

Synthetic is the best for every engine and contrary to old wives tales you will be just fine switching to synthetic. I like Amsoil, Mobil 1, Penzoil Synthetic and others are great oils.

 

The only issue when switching is that gunk build up that plugged holes that would otherwise leak will be cleaned out & you will find leaks.

It's a double edged sword. You could have a problem on your hands, but at the same time, you know about it much sooner. That said...

I got my 09 w/ 106k miles & have been using synthetic for the last 30k miles. No leaks.
I agree w/ Calif Phil. Get a quality brand. I usually buy Valvoline or whatever quality synthetic is on sale. Just don't mix brands.