I only use AMSOIL (synthetic 2-stroke) in my PWC, plain old Castrol GTX white bottle 5-30 in the cars, and MOBIL-1 5-30 in wifes Sedona (same 3.5L as XG/Santa Fe)

 

Will 5w30 affect the camphasers and oil control valves that are controlled by ECM?
I know 5w20 is on the oil cap but it tends to shut up the rattle on startup. Which I have been tolded by Hyundai tec is normal.

 

Using thicker oil to quiet the rattle is not fixing the problem. Keep using 5w20 and fix the rattle. It has to do with a loose timing chain tensioner. It's very common on the 3.3L and 3.8L Lambda engine. Get it fixed by the dealer under warranty. Tell them about TSB 08-EM-001-1.

More info:
https://www.hyundaiforum.com/forum/s...ead.php?t=9019
https://www.hyundaiforum.com/forum/s...ead.php?t=6621

 

sorry the hyundi tec said the noise was normal and there are no problem with the tensioner.
Rattle ranges from 2 to 3 seconds not every time just after I drive 30 minutes or more i will drive next week to tampa from atl and when I restart after I stop after supper it will be noise. Oh! the dealership replaced my mobil 1 5w30 for there 5w20 kindell oil.