[maxaccel]

C / K....... you may wish to reacquaint yourself with Castrol's website.

See if you had, you'd have had a different title for your thread.

More like -

" 2005 Silverado Vortec 5.3L w/ infamous < incorrect oil induced > lifter (?) tick on cold start "


Plain 'ole Castrol GTX 5W 30 lost much well over five or so years ago...... including somewhere around that time, Castrol's own recommendation and listing for use in your application.

You may want to root around in there and also elsewhere ( including GM's deros listings ) - if you feel like it concerning which Castrol engine oils are on Castrol's own recommended list ( no GTX xxxxx product currently is ) and then separately, which Castrol engine oils - while not on that list..... at least carry a usable GM spec for your specific application.


The Product Data pages are your friend.

Although currently and more than somewhat oddly given what else they list, they do not have one for 'plain' Castrol GTX 5w -30 ; while the other weights / grades are still up.


You will find some Castrol GTX xxxxx 5w 30 product that second, more often than not, inferior way.


Trust me, derros 1 and deros 2 are your also your friends.......

Matter of fact, Castrol GTX Magnatic 5W 30 appears to have been put together as a GM oriented 5W -30 service oil. ( GM6094M / deros 1 )

Notice though, they do not recommend it when you punch in your vehicle which at the very least is somewhat largely about USA availability -

Anyway, there are others for poorer but also acceptable consideration - if you just have to save the very last dollar or two - per jug.


Look for GM6094M / API Starburst ...... or for far better effect in almost all cases but not necessarily all given the relevant Castrol specifics - deros 1 or if you prefer...... deros 2. Plus the Starburst.


And remember, Castrol like literally anything and everything BP bought - after their Goldman Sachs 'refresher course' on how not to be a good POL provider but make a lot more money anyway is all sloppy like with their website.


Btw, you are not alone with regard to this sort of thing ie where a perfectly serviceable oil lost large swatches of it's original suiteability - for your vehicle over it's service life.

Good advice,
I use Castrol 5 -30 aso,,,, on my mechanics recomendation..used to live in Edmonton Alberta many years where it gets minus 30 every winter,,put 300K on my 2000GMC pu without any engine problems