I bought a new to me 2012 5.7 1/2 ton 4x4 and according to the book it claims run 5-20 weight oil. Here in central Texas it gets hotter than hell and that just seems to light so I put 10-30 in it, anyone see a problem with it?

Absolutely no problem in my opinion. I ran 5w40 synthetic in mine with no issues when I had it. I think the factory user manual even talks about a heavier oil for heavy duty use, might have been 10w30.

I'd run 15/40

Heavier oil may effect the MDS feature of the 1500, but the 2500/3500 trucks call for a 5w-30. 

 

That being said towing will have a much larger effect on oil temp than ambient temp will, as the coolant heats the oil up more than ambient. If you don't tow with it then 5w-20 is likely fine for all conditions and may yield slightly better mileage...which is why they recommend it. 

Edited January 10, 20205 yr by AH64ID

One thing to remember, especially with those newer Rams (and likely most newer makes) is that a lot of these specs are chosen with efficiency and emissions goals and long maintenance intervals in mind, not the lifespan of the vehicle and it's associated parts. I think we do have to put some trust into the manufacturer's recommendations, but I trust their judgement less and less as the years go by. 

Yes and no. Modern machining on stock engines is probably as good as, or better, than custom machining 20-30 years ago. Higher rpms and higher power outputs have demanded an improvement. Things have come a long way and manufacturing tighter tolerances will allow for thinner oils without longevity issues. Oil also isn't what it used to be, its MUCH better. Things get better, but change is sometimes hard. 

 

Yes thinner oils are there for efficiency reasons, but it may not be a bad thing. If the application is a 1500 that doesn't tow I'd have no issues running a 5w-20. If you tow frequently then a 5w-30 is probably a better option. A 5w-20 synthetic is probably perfect for occasional light towing.

 

I did noticed that in the 2014 manual it talks about above and below 14K GCW for 5w-20 vs 5w-30. In the 2018 manual that blurb is gone and it just states that 5w-30 is acceptable for all platforms if 5w-20 is not available. 

 

There is nothing wrong with longer maintenance intervals on modern equipment. Between the improvements in the machining and the excellent fuel injection the oil isn't abused like it was on carborated or older EFI systems. 

 

I did have to laugh when I got my 05 TJ with a 4.0 thou. It was the 2nd to last year of that motor and maintenance intervals were the same was when it came out, 3K/3mo. There is no way in hell I'm changing the oil that often, it's absolutely not necessary even on that old tractor motor. It will get 12 month changes with good synthetic and good filters, and I'll save money and time. 

Edited January 11, 20205 yr by AH64ID

The only thing I will mention is the 5.7L Hemi has had issues with rear cylinders and the con rods popping out the block. I've seen two already that have had this issue locally. One happened to be a close friend and his wife's 5.7L Hemi Durango.