Hey Matt, thanks for the tutorial. My specific question regards reading those two top rows. Is that read as: at 100F either 20W-50 or 10W-50 are appropriate?The thicker the motor oils ffilm in mil's is , the greater it protects the 2 metallurgy surfaces that it is designed to do ...
motor oils primary number 1 mission is cooling , reduce heat from friction of metal contact to contact while moving also against each other , hence less breakdown and loss of metal over time , so this = tight clearances and tight like new tolerances m same as plasti-guage when you install new rod and main bearings
the thinner the viscosity , less oil film mil's , heat thermal is UP HIGHER , and now metallurgy wear and tear is going on FAST
think of drilling a hole in a frame rail , u keep drill bit COOL using OIL right ? this = long sharp bit life and even nice hole in metal too , NO BLUING of either bit top or frame rail ....
u use water or say WD-40 as a lube oil drilling same as above , it WILL SMOKE OFF FAST and blue drill bit tip and metal frame hole too ...
and drill bit tip gets DULL fast and can snap and break too
does this exacting details same as inside a engine theory applied here make better sense ?
the oem FSM viscosity chart is saying use the THICKEST possible motor oil for the greatest protection and anti-wear factor possible , as it relates to your outside climate temperature range it spells out ..
its a bit of give and take and achieving a optimum balance to keep the highest possible protection level you can
here is DC east coast today in January its currently 46' F , unusually warm fot this time of year ?
but , is it now with hotter and hotter winters globally , as the earth continues to get hooter each cycle around the sun ?
i am now today at its 10W40 ish range , closer to 20W-50 , .....
matt