2004 Tahoe LT 5.3L, 120,000 miles, has had conventional 5-30 oil since 2004 to present. Went to WalMart 1/27 for a LOF and was assured conventional 5-30 would be used.
Turns out a Pennzoil 5-30 synthetic blend was used. No one could tell me what what percentage of dino to synthetic.
Should I be concerned ?
Thanks

 

NO concerns - I run full or blend in two vehicles that are over 350k; once upon a time changing was said to cause leaks - apparently not true

 

I only buy cars new and then only because used cost almost the same as new. But all my trucks I buy used - and some of them Well Used. <g> My father ran the refinery attached to the Mobil Research lab that developed and tested Mobil 1. I was routinely subjected to all the scientific chatter the research lads and the test-stand boys were not supposed to be talking about. Based on their enthusiasm I switched to Mobil 1 when it first came out. Although . . . my father never did. <g> He continued to use the Mobil oil that came in gold cans - I forget now what it was called.

But I used Mobil 1 in everything and have ever since. And what I found is that all the negative rantings from the armchair-experts was nonsense. Every single difference has been positive. So I find it very hard to imagine that your experience with Pennzoil's synthetic will be anything but positive.