For several years now, Mobil has been the oil supplier to Mopar and Purolator makes their oil and air filters. I don't think the 5w20 is synthetic though. Probably the reason for the confusion lies in the fact that many people think of synthetic oil when they think of Mobil. But only the Mobil 1 oils are syns.

 

I have an '04 5.7 and changed the oil in it the other day and noticed that on the oil cap it says 5W-20. I put 5W-30 in it since I grabbed it...thats what I get for not paying attention.

 

This topic needs updating because, earlier this year, Mopar signed a new contract for an oil supplier. They signed a multi-year contract with Pennzoil to be the new supplier of Mopar packaged oils. Purolator still produces their filters.

 

IDK what oils they are putting in the 4th Gens but the 3rds were not getting synthetic in the engine oil. Trans and rear was synth though

 

Any oil that the manufacturer provides in their oil tanks is Conventional oil!
Only time you will see a Synthetic is where a vehicle specifically calls for it and will usually say it in the owners manual and on the oil cap sometimes. Viper, Vette, Porsche, pretty much exotic cars. Ceratinly no regular pick-up truck like a Dodge ram will see Synthetic. They are made to be the cheapest Buy of all the competitors. Synthetic oil would cost them too much.
So it's Regular conventional oil in the 4th Gen's. As far as the transmission goes, the Mopar ATF+4 is actually not a true Synthetic blend but has properties very similar to Synthetic, therefore if you were to replace the transmission fluid, either ATF+4 or an ATF +4 Synthetic equivilant should be used to match or exceed the OEM fluid properties. Standard Mopar trans fluid is a conventional fluid that has Lubrizol in it which is how they skirt around the true Synthetic nature of the compounds. It's much cheaper for them and provides very similar results.
Any company who slaps ATF+4 on their fluid needs to have Lubrizol mixed in. ATF+4 equivilants are generally Synthetics. Think about all that while your price matching Mopar vs other brands. I did have a list of all the suppliers who are Lubrizol certified but I don't have it anymore. Most of the larger brand names are using Lubrizol.

 

The list of licensed ATF + 4 brands is here:
http://www.centerforqa.com/licensedatf4brands.html