I asked the dealer why Ford used 5w-20 the last time I was in for the Eco-Boost challenge test drive to get a $50 gift card in the mail. Now keep in mind it was a dealer service manager I talked to, and we know how they can be, but his answer makes sence to me. He said the engineer told him when they started to back spec older cars, (which are not affected by CAFE standards) that Ford has thought thinner oil was better for start up, economy and upper engine lubrication for many years, especially in colder climates. And Ford was actually late to the 5w-20 party. Most other automakers where working on it before ford. The problem was oil durability. 20 weight oils just didn't hold up then. He said once oil advanced far enough that a 5w-20 could last beyond a recommended oil change interval, they where able to safely recommend it. He also said the thinner oils warm to operating temps faster and are more reliable for operating things such as cam phasers, but admits the oil controlled cam phasers weren't the best idea. The adviser also told me he remembers when auto makers started using 5w-30. He said people complained and thought their engines would fail early and some said it was a trick to make the vehicle die early to sell more cars. Some folks even demanded 10w40 be used in their cars and then complained when they were hard to start in the winter. Because most of the Eco-Boost engines tend to be harder on oil so they use 5w-30 to ensure it lasts for the recommended oil change intervals. He thought 5w-20 would be better for them too but would have to be changed too often and would not be cost efficient. He was willing to bet in a few years they will use 5w-20 as well.
While a dealer service adviser is obviously biased and wants you to feel good, and they do not always have as much knowledge as they think, It makes sense to me. My cars have had no issues with 5w-20 and I am hard on them. My Focus was even neglected and saw a few 15-20,000 mile oil changes with conventional 5w-20. It just turned 179,000 miles and the only engine issue it has ever had was the valve cover gasket. It runs great and still has good power. It has picked up a slight knock when it's cold that goes away after a few minutes. I think a 0w-20 would likely quiet it down sooner. I am sure the engine will out last the rest of the car. My 1969 snow blower with a Briggs engine calls for 5w-20 in the winter so I know it has been around a while.
While a dealer service adviser is obviously biased and wants you to feel good, and they do not always have as much knowledge as they think, It makes sense to me. My cars have had no issues with 5w-20 and I am hard on them. My Focus was even neglected and saw a few 15-20,000 mile oil changes with conventional 5w-20. It just turned 179,000 miles and the only engine issue it has ever had was the valve cover gasket. It runs great and still has good power. It has picked up a slight knock when it's cold that goes away after a few minutes. I think a 0w-20 would likely quiet it down sooner. I am sure the engine will out last the rest of the car. My 1969 snow blower with a Briggs engine calls for 5w-20 in the winter so I know it has been around a while.
