Originally Posted by
itschad
I remember having cars that weren't fussed, a 20w 50 oil seemed to work in all cars from the 60's to 70's then it all went nuts,this spec, that spec one grade of oil wasn't suitable for all cars, you had to study numbers, letters and Lord knows what else.
Improvements in technology have lead to synthetic lubricants that flow better at colder temperatures and hold their viscosity longer. Research found some additives were harmful to the pollution controls, which led to new formulations.
Here's more reading from experts on the subject.
Blackstone Labs | A Brand New Perspective: Digging Into the Timeless Question, “Which Oil is Better?”
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View my fuel log 2015 Mirage ES 1.2 manual: 49.6 mpg (US) ... 21.1 km/L ... 4.7 L/100 km ... 59.5 mpg (Imp)