which oil is best ...

[20psiGMC]

Re: which oil is best ...

My mechanic put Castrol Magnatec 10-40 in my truck, but the problem is that this oil is blended, not pure synthetic.

Can someone tell me if it's dangerous if I drive 2k miles with this oil??

Temperatures will reach 100 degrees next month here.

TIA,
Pedro

It's been my experience that Castrol is decent oil, and among the better grades of mineral oil. From their website, the Magnatec looks to be an Ester-synthetic blend, which is a good thing. I think you’ll be fine. If you don't have a pre-luber/turbo-timer, remember to allow the truck to idle for a little bit - a “cool down” period - before shutting it off. This is a good practice even with a full-synthetic oil, especially after a hard run.

My :2cents: