Correct me if wrong! If hes casing low price just to use blend aren't you suppose to stick with that now and not go back to conventional oil.

 

Personal prejudices aside, these engines will be just fine with whatever type oil you choose to use. They were designed in an era before synth oils were common and many have gone well over 100K miles on dino oil. That said, switching to semi or full synth will do no damage and may make you feel better about your engine.

 

Thats a myth, you can go back and forth as much as you want

 

I guess you don't know what a blend is if you made this statement. A blend is part synthetic, part dino oil. The "once you use synthetic, you can't go back to dino" statement doesn't make sense anymore when they came out with a synthetic blend.

 

I have used synthetic blend in my first 2001 blazer for most of the 13 years years we drove her. Keeps the engine real clean inside. When I had a valve spring break at 213k the top of the heads looked like new almost, very clean. Wish I had taken pic now.

 

You can switch back and forth with synth. and dino oils without problems. Be aware if you go to synth. and have used only dino oils, you will notice that the first synth. oil change will get dirty very quickly,i.e. turn black. This is showing the cleaning effect of synth. and it is a good thing. After a few intervals of full synthetic this will go away.
In fact if you buy a used Blazer and think the oil changes were neglected by the previous owner, run full synth. for two or three oil changes and it will clean the engine. Then if you are on a tight budget, go to a good dino oil such as Pennzoil with a good filter with OCI of 3,000 miles. If you can afford it, stay with the synthetic oils such as Mobil 1 or Pennzoil Platinum/ Ultra. It will be worth it in many ways.