Originally Posted By: earlyre
Plenty of 5w20 conventionals exist. Since this is the5.7, not the6.1,or 6.4, 5w20 conv. Will be fine. There's even anecdotal evidence of those engines having some issues with engagement of the vvt when a 5w30 is used.
Pfffffffft. I've got 0w-40 in my mds hemi right now and there's not any difference in how the mds engages.
OP. I had an 04 ram hemi quad cab 4x4 and it got 5000 mile dealer bulk 5w-20 all its life til I got it at 240k. Truck ran like a dream,didn't consume a drop of oil between changes and had no problem towing my brothers dump trailer across the province and city dump runs with 7500 pounds on the scale.
You can use whatever oil you like in that thing however don't give a second thought to the too thin pipe dream. I totalled mine at 280k and that hemi is the only reason I bought my charger. Reliable and long lasting and it got nothing but 20 grades its entire life.
I ran a 5w-20 in my current hemi up til the last change. I had liqui-moly 0w-40 in stock and because winter is coming I went a bit thicker to combat the inevitable fuel dilution that comes with the extended idle times winter brings.
Be advised that the ecu may throw a code using an oil thicker than a 20 grade however in my experience mds engagement in unaffected.
It's quite possible that mds engages milliseconds slower with thicker oil and I've seen evidence of this however in real life its not measurable.
I was always a thicker is better guy however my last hemi has helped me see that in real life,in an engine that calls for it,wear control is a non issue.
I can say for certain that with the 20 grade in the sump the engine revved much more freely,spinning up quicker and taking longer to return to idle speed vs the 40 grade I'm running now.
I mixed in a quart of Pennzoil Platinum 0w20 with 5 litres of 0w-40 just to bring it a bit closer to the desired 20 grade,and I had it in stock.
If you're under warranty I suggest you use the 20 grade dodge calls for. Thicker oil will throw a code that the dealer will see,so personally I would just avoid the issue altogether but if you're not still under warranty go ahead and use up what you've got.