2005 Dodge Dakota takes SAE 5W-20 viscosity grade engine oil. SAE 5W-20 are commonly recommended for use in many new vehicles with modern engine technology for maximum fuel economy and performance.
Multi-grade viscosity motor oils are able to perform at a wide range of temperatures. For an SAE 0W-20 oil, the “0” is the cold-temperature viscosity rating (the "W" stands for "Winter"), and the “20” is the high temperature viscosity rating. Multigrade viscosity motor oil flows well at low temperatures, but still protects the engine at high temperatures.
For comparison’s sake, SAE 5W-30 and SAE 0W-30 will flow better at colder temperatures than SAE 10W-30, while still providing protection at higher temperatures. See more at Pennzoil.com.
To view complete 2005 Dodge Dakota specifications, see this link: http://www.rockcrawler.com/features/newsshorts/04february/dodge_dakota_specs.pdf.
Get tips on choosing the right engine oil from Edmunds.com.