Motor Oil 5W-30 Synthetic Blend
 

Folks,
I have 2002 I35 with 170K miles on it. For years I was using conventional Castrol GTX 5W-30 for regular oil change. Castrol has eliminated conventional 5W-30 in 2016 and started using synthetic blend for GTX ultraclean and for GTX High Mileage oil. I stayed with Castrol and started using GTX high mileage. I was not happy with switching from conventional to synthetic blend but proffered to stay with Castrol brand. The car has developed small oil leaks, so once in while there is a smell of burning oil.
I could be from the age of the car where seal have deteriorated or could be from using synthetic blend oil.

What is your opinion on this subject and what is your experience if you are using synthetic blend?
Thank you

You open up a can of worms whenever you bring up motor oil-- everyone has their own opinion and everyone else's opinion is wrong.
Here's mine: Just switch to another brand. Why do you have to stick with Castrol? Hell I use WalMart SuperTech in mine and it's fine, it's what I used in my Maxima and I put over 400k miles on that thing. Or if you insist on a name brand, switch to Valvoline. It's almost always ranked at the top of motor oil ratings lists, and they still offer 5W-30 conventional. $18 for a 5qt jug of it at WalMart.