initialgemini

Well said. I'm sure the manual recommends using only nissan brand coolant, but does that mean if you use another equivalent brand that your radiator will corrode? Most likely not.

Using synthetic oil is considered to be better for engines because of high grade of purity for its chemical make up. Think of it this way, not all oil molecules are made equal. In you typical brand of oil, there are variations in the chemical make up of the oil. They have the same chemical formula but not the same properties, also known as isomers. As an oil, it must contain a certain percentage of specifically oriented oil molecules in order to pass quality. Synthetic oil is chemically altered to eliminate isomers and have a higher chemical purity. Isomer oil molecules affect your engine in that their chemical properties such as a reduced heat capacity before breaking down. Synthetic oil is thought to be superior because of it higher chemical purity. The addition of esters is merely a stabilizing compound which is found in many full synthetic brands.

The key to oil in the engine is providing it with a specified oil by the manufacturer and staying consistent with its recommended viscosity rating. Not only does the oil lubricate your engine, but also keeps the seals lubricated as well. its okay to go from a lower to higher viscosity such as 5w-30 to 10w-30; however, going from high to low is asking for leaky seals and oil leaks. Just to clarify, the first Xw refers to the viscosity rating at cold temperatures and the later is the viscosity at operating temperatures. As long as you are using the appropriate weight oil and preferable a full synthetic, the engine should theoretically run fine.