So i have a newer nissan armada

I put "blended" oil (some special half syntetic half regular oil) in it one time at a jiffy lube type place

Next time I went back there they said they were out and I put pure synthetic oil in it. Problem is it was like 80 bucks for the oil change

Now that I have had sythetic once (or one and a half times really) can i only now use synthetic oil from now on?

I think I heard that once but want to see if its true.

Not true, you can switch back and forth as you desire!

Old Wives Tale.  I still prefer dead Dino.

I have a 08 Nissan Titan. Same engine and transmission as yours. I use full synthetic, but change the oil myself. It runs me about $40 for an oil change using Pennzoil Platinum 5W-30. These are also the simplest vehicles ever to do an oil change on. You can actually grab the oil filter with both hands.

You can switch back and forth all you want between synthetic and regular oil. Check out Bob is the Oil Guy. Go to the forums there and you'll find all kinds of information.

Here is my lab test from Blackstone Labs using Amsoil 0W-30 fully synthetic oil. These Nissan engines wear really nice.