Yes they are extremely long manuals now, it is aweful in a PDF. Most people do not get comfort in nuance. (People like prescriptions so when they see. "Use this" statements from an authority provides comfort, human behavior can easily be influenced this way.
It is easier to follow specific Instructions such as "use 0w20" it's what the manufacturer recomends.
But to say it's ok to go up in oil grade for harder working engines but not break the EPA/CAFE (cars must recomend oil used in mileage sequence test) oil recommendation language requirement is a semantic tightrope (and nuance not specs)
In the end 0w20 is fine for the majority of American drivers. The type of driving a Prius gains the most in mileage/economy is exactly the type that 0w20 also is doing its best in protection and economy. (City and suburban milage).
Going up in oil weight for me is because I see my use as outside the USA norm, (I do a lot of off-road driving(lowmrange mountains, high range deep sand)and higher than US average highway cruising speeds)I use the modes of lubrication and hierarchy of controls. Hydrodynamic lubrication is a safer/lower wear control than boundary. I see higher HTHS as a quantitative control measure to maintain that type of lubrication. Of course all control measures have a cost.
Originally Posted by ekpolk
Originally Posted by Bryanccfshr
Page 748 of your owners manual actually does have the allowance.
â– Engine oil selection
. . .
By the way, the Owner's Manual for the 2018 Prius does not even have the heavy use or hot weather recommendation to use a 30 wt oil. It's absolute -- it says use 0w-20 at all times and in all conditions. We are allowed to top off with 5w-20, but are "cautioned" to replace it with 0w-20 at the next change. No other oil viscosities are even mentioned at all, nor are any "extreme" conditions.
Thank you Bryan, you are correct, I did miss that reference. Excuse (pretty pathetic...): I've only had the car ten days, and the manual for three days (had to be shipped, original was lost). And the darned thing is 820 (yes, EIGHT HUNDRED and twenty) pages long! The manual for the 04 Prius was only 300-something pages! It looks like an unabridged dictionary!
Anyway, even with that language in there, I don't see much difference in approach, especially since they don't specify what they mean by "high speed" or "extreme load" conditions.
If I observe undue consumption, I'll probably check with a UOA and evaluate from there. I was tentatively planning to do a UOA at the 10k mile point to establish a baseline, so we'll know early if 0w-20 possibly isn't up my higher speed, hot weather, medium load driving. History has already spoken in the broader sense, but time will tell with this car. [/quote]
