Conventionals work so good but the comparison charts show the performance and cleaning and such as very low. I guess they are trying to sell synthetics. Look at Valvoline and Pennzoil. I think an uninformed person could look at those charts and feel the need to get the synthetic because the conventional is rated so low.
http://www.pennzoil.com/motor-oil/
http://www.valvoline.com/our-products/compare-motor-oil
http://www.pennzoil.com/motor-oil/
http://www.valvoline.com/our-products/compare-motor-oil
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