Just to be clear here. The "0" viscosity has to do with the lubrication capabilities at colder temps and the ability, if needed, for it to flow at lower temps to help lube at start up and warm up. It then changes to the "20" viscosity to lube at higher ambient and engine temps. If in an area that is higher temps then the "30" viscosity is available and that seems to be, especially with synthetics, the norm nowadays. It is very rare for a viscosity of "40" to be called for. Engine builders and designers want that oil to FLOW for better lube and protection.
If I messed any of that up, please correct me. Also, engine oil requirements and certifications are very important and must be met and of course, use a damn good oil filter.
If I messed any of that up, please correct me. Also, engine oil requirements and certifications are very important and must be met and of course, use a damn good oil filter.