Just bought an 06 1500 Big Horn 5.7 Hemi. It had 50,000 miles on it so I wanted to switch over to synthetic oil and I used mobile 1 5w 20. I was looking at Amsoil's website and it actually recommended 0w 20 as the best so I wanted to know what everyones opinion is on this, I used 5 w 20 because that's what the manual said. Also thanks to everyone for their help and advice on here.

 

Not really much of a difference. The 0w20 would would flow slightly better when cold, no difference when hot. That's the theory, but if you review independant tests, the actual weight actually can vary from the manufacturer's classification. I like the "zero" weight oils, but if you have any doubt, go with the weight on the oil cap 5W20.

 

My understanding is that it needs 5w20 for the MDS to work (I can't remember if the 06 has MDS or not, but I think it does).

I switched everything over to full Synthetic at 30k miles on my 08.

 

Yes it has the MDS. I will just stick with the 5W 20 since I live in Southern California and the cold weather isn't an issue. Thanks guys.

 

0W-20 and 5W-20 oils are both 20 weight oils when fully warmed up. While different brands can be a little thinner or thicker they still will fall into the 20 weight viscosity range at operating temp. So, either one is ok to use in a vehicle that calls for 20 weight oil. Even a HEMI Ram with MDS.

The 0W and 5W part simply indicates the oil's cold flow viscosity. The benefit to a 0W-20 over a 5W-20 would be improved flow at cold start which really is only an issue if you live in a really cold climate. Synthetic oil by it's very nature retains it's cold flow pumpability to a very low temperature range( well below zero )so even a 5W-20 has no real issues in the cold. As you said, you live in CCA so cold starts are not really a problem for you.

The 5W-20 you used will be fine. I believe Amsoil offers only 1 0W-20 oil which is their ASM line. It being 0W-20 doesn't make it better than the Mobil1 5W-20. It would only be better if it used a superior base stock and additive pack which it happens it does. It isn't better because of the weight.

 

0W-20 and 5W-20 oils will work with MDS. It is the "20" part that matters. Chrysler only spec's 5W-20 because the FF oil and oil spec called for are based on conventional oil. 0W-20 is only available in synthetic.