I'm bored so I felt like spreading info.
Many split port (non zetec / dual overhead cam) engines found in many Ford focus's are siezing. Alot of engine builders are seeing the bottom ends grenading.
Use 5w20 if it calls for it. Thicker oil (especially thicker viscosity dino oils in cold ambient temps) are cavitating the conrod bearings and siezing split ports everywhere.
2 customers that get oil changes from quick lube shops throw any type of viscosity in their cars. Both bought their cars new. Both are 2002 split port Focus makes (1 with 100,000kms and the other 130,000km). 2 siezed motors in non abused grocery getters.
Dont mess with recommended viscosity suggestions. Tighter bearing clearances are not like the old days.