Motorcraft Synthetic Blend Sure, Ford wants to sell motor oil. But we have to recognize they spend lots of bucks developing the right lubricants for their engines. Their recommendations make sense, not only for lubricity and performance, but also mileage and keeping pollution as low as possible. Their 5W-20 Synthetic is engineered for all weather conditions likely to be encountered. Plus, I have read that the warranty may be voided if the wrong oil is used in the newer Mustangs. Not simply using non-Ford branded oils, but using other than the 5W-20 synthetic blend. That would be a shock to have Ford have the oil tested and find it was a 15-30 or something and hand you all the pieces back to fix at your cost! I have a 2003 Mach 1 and the mileage and performance are every bit up to expectations. I was a semi-pro racer for years and used every type of oil you can imagine, some developed strictly for the high RPM's and heat encountered during racing. But, the factory seems to have the lock on what's best for the new vehicles. Plus, like the man said, at $1.77 at WalMart, how can you go wrong? This certainly does not apply to all year Mustange or higher mileage cars. If you look at the Ford Specs for oil for these vehicles, you would be amazed at the engineering that goes into the simple choosing of the right lubricants. Be safe and have a Happy New Year!