0w-20 or 0w-16 oil? manual conflicts

Personal choice I guess. 0W-40 Mobil1 is a great pil nobody mentioned. I'm are you can see why. Their rebate brings it down to$13/gal too. Change it hot and 4 quarts come out cold (don't start engine in morning and drain it where it sits) and 6 quarts come out. VVT holds a couple quarts of dirty oil.

 

Interesting that 0W-40 is not listed but 15W-40 is? I would think 0W-40 would cover all the basis. I currently use 0W-40 and its works great.

 

Some repair manual info:



According to the above there's roughly 0.5 liter (0.6 US quart) still in the engine after after a regular oil-and-filter drain.

 

I wonder how much others drain cold?

 

I've never drained cold - as hot as I can, particularly with older cars. As far as I can remember, all my cars have said hot:

MAZDA 929 1984 "Drain ... while the engine is still warm, be careful not to burn yourself ...";
VOLVO 244 1980 "Start the engine ... reach normal operating temperature - oil and sludge will flow more easily when warm ...".

 

Our Toyota dealership here in Saudi Arabia uses 5W40 exclusively for all Toyota vehicles and that's probably to do with our hot climate.
You can see below what my 2017 Saudi spec Prius manual says regarding oil recommendations .

I am thinking of trying 0W20 weight oil to see what changes in terms of fuel economy and engine characteristics when starting from cold .

 

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OW-16 weight oil has been used in Japan since 1990 to reduce fuel consumption and the major Japanese refiners are experimenting with OW-8 weight oil !!! The American automobile manufacturers don't use such thin oil because their engine machining equipment is not accurate enough to maintain adequate oil film thickness with such low viscosity lubricants. Furthermore, most American auto manufacturers are focused on manufacturing trucks,which are much more profitable and require higher viscosity oil. The American auto manufacturers they have virtually abandoned the idea of competing with the Japanese by making fuel efficient cars.
Dennis Waller

 

Why not go whole hog and just use water then??

 

Water has very poor lubricating properties.

 

I wonder how much effect, if any, thinner oil has on the hydraulic tappets (lifters) ?

 

If they're designed for the oil, should be fine - along with oil pumps etc. I imagine if I used it on, say my '70s Renault or VOLVO, because they were designed for something like 20W40, they wouldn't be happy. - or our '49 Austin which wanted SAE30.

But modern engine components are designed for the better oils. And - I suspect if you put 20W40 or SAE 30 in a modern car, it would seriously compromise longevity.

 

These thinner oils are crap! Most all new cars sold in the USA, including domestic are using 20W oil. This all has to do with CAFE standard, not that they are better. If they were better then the same car sold in other parts of the world would be advised to use 20W as well, and that is not the case. I personally use 0-40W oil and the cars runs great, with no oil use!

 

1). 2009 Corolla, 51,000 miles. 0W20. No problems. Recommended interval 6 months. 2). 2010 Prius 3. 36,000 miles. 0W20 synthetic. No problems. Change interval 6 months. 3). 2013 Prius 3. 34,000 miles. 0W20 synthetic. No problems. Change interval 6 months. 4). 2016 Prius 3. Now 24,701 miles. 0W20 synthetic. No problems. Change interval 12 months.
I don't know what I don't know. So, I try not to out-think the experts who advised me to follow the above patterns of behavior.

 

5quart 0w16 $14.99 sn+ rated at Walmart

Honda Green oil has Ben 0w8 since 2001

 

If your going to keep your car past 100K miles, your going to see oil usage on the 20W. But its your car do what you want.

 

Is anyone else using 5w-30 oil on their gen 4 prius? I have read this whole thread...and am still a bit confused. I'd like to protect the engine a bit more than 0W-20...and I live in Southern California where I worry more about the other end of the temp spectrum more than sub zero weather.

 

The manual says if you use 5w30 you should change every 5000 miles.

 

I think it says 5W20 in that context, in manuals spec'ing 0W20. And 0W20 in years where the manual spec's 0W16.

5W30 is an interesting option, was the spec for second gen.

 

All low miles - give it some time.

 

The reason for thicker oil use on the Gen3 is because it is suggested in other parts of the world. You should try to research it more for the Gen4 and see if other parts of the world are using thicker oils in them. Australia maybe one of the countries to investigate.