One way to reduce friction in a car engine is to add?

Question

i really need this answer please help me if you can

Answer 1

is it oil?!!!

i mean are you looking for something else?  

Answer 2

The best lubricant used by professionals is Royal Purple.  Often lubricants have a service life of only 5,000 miles due to oxidation which reduces oil's ability to lubricate. Oil's ability to resist oxidation is measured by the ASTM's rigorous Thin Film Oxidation Uptake Test (TFOUT). Royal Purple surpasses leading mineral- and synthetic-based oils in this test and also outlasts the duration of the test.  Royal Purple's superior oxidation stability enable oil changes to be extended to 12,000 miles, saving money, saving time and reducing the amount of used oil that must be disposed of.

Answer 3

I would say oil - but that's too simple yes?

So I'll say Molybdenum Disulphide to the oil- as a high pressure lubricant.

It is a dry lubricant that acts to fill the irregularities in the machined metal surfaces