There is some confusion out there over the proper viscosity for the 6.1 and 6.4 Hemis. This is because of Dodge switching oil brands. Originally, Dodge recommended 0W-40 Mobil 1 synthetic for the 6.1s (that was the factory fill). Then, in 2011, the recommendation became 5W40 since Pennzoil (the new factory fill) did not have a 0W-40, domestically. Now, that Pennzoil has 0W-40, the recommended viscosity has reverted back to 0W-40. Both Mobil 1 0W40 and Pennzoil 0W-40 meet the required Chrysler specs for your Challenger, so you can use either one. If your mechanic used 5W-40, check to make sure the specific specifications noted in the owner’s manual (MB229.3, MB229.5) are on the oil bottle.
What weight Oil Are The 5.7's Using. In Particular mobile 1, I Was Looking Today and Walmart Had 0-20W And 0- 30W. I'm Going To switch My next oil change. What Is The Consensus ? Thanks Rosco