I want to switch from Amsoil 15w 40 to a cheaper syn or dino. Is this OK? any thing i need to worry about. If i stay syn i would use Rotella 5w40. Is this ok to use year around living in southeast texas. Or should i go with Rotella 15w40 dino. Whats the scoop on other 15w40 dino oils. Delo 400? Mobil delvac1300? Castrol diesel? Coastal deisel? One last thing about Rotella the 5w syn is basically like 15w dino. There is no such thing as 15w40 syn in Rotella. Right. What would be the changing interval on the Rotella 5w40 syn? Thanks for y'alls advice.

 

The Rotella-Syn is a good one and I use it year-round. It is API rated and any brand that carries the API rating of CI4+ is a good oil to use.

Rotella-Syn is less expensive than other synthetics as it is a highly refined group III dino oil (meets all synthetic reqirements). Mobil's synthetic is a PAO group IV synthetic (true synthetic).

Living in Texas you may be fine with 15W-40 conventional oil with frequent oil and filter changes. Synthetic offers better cold weather and high-end heat protection... but either should serve you well.

Even using synthetic, I change every 5,000 miles (oil and filter). The 6.0L motor likes clean fresh oil more than any other motor I have had... so even running synthetic... I change every 5,000 miles.

You should be fine on whether you pick conventional or synthetic oil... but it is more important to change oil and filter every 5,000 miles than the type of oil you use... just use one that is CI4+ API rated or the new CJ4 rating.

Good luck,