My experience using 5W-40 instead of 0W-20

After I went to 5W-40 my fuel economy jumped to 65mpg. I was getting 60mph on 0W-20 but I was like whoa, can this really be happing? Then I went to 15W-50 full synthetic Mobil 1 because I heard so many good things about it. Reports are pending.... Amsoil experts might be right!

 

Is that a full tank calculation? Short trips mean nothing. Refuel after driving 500 miles. Go thru 3 full tanks, and then report back with the MPG. Hand calculated.

 

I'm a little incredulous. I've never got 65 mpg, period. And with a thicker oil?

 

Agreed. Hard to believe. 50W oil in a Prius???

 

50w oil? In the Prius? Even for a newer non Prius engine that's high! Makes the engine work harder.
Might not flow as well either, which could cause over heating, and circulation problems, worst on a cold engine.
It would be WISE to pretty much stick to way the manufacture recommends for THEIR engines. They would know.
Thicker oil does not mean better fuel mileage. Perhaps you miscalculated? Best to do as says, a few tanks ....

 

Now, if your talking 5W-30 Mobil 1, I'm all for it. Better long-term engine wear protection, in my hot area. (That's the theory, anyway. )

I'm on my 5th tank of gas since switching to the "Extended Performance" Mobil 1, and I believe my ICE is definitely a little smoother & quieter when accelerating. And It was especially noticeable at idle. When I'm parked somewhere with the AC running, and the ICE kicks on to recharge the battery... the engine sounds much better.

Gas mileage? Just slightly better, 2 or 3 mpg, max. But it varies and may not be related to the oil. My last 500 mile tank was 56.5 mpg calculated. All stop & go city driving. PWR mode. (And I also decreased the tire pressure back down to factory specs. Better ride, and better oil. I'm sticking with it.)

What happen to BuickGM, the oil guy???

 

Yeah considering 5W30 was second gen spec, not much of a reach.

 

And is still recommended (or at least an option) for the Gen4 in Europe? Asia?

 

I drove all day with 15 w50 stopping only for lunch. I was like Wow could this really be the case? My battery charges faster and my transmission no longer whines when I get on the brakes. Amsoil and the orange filters from Walmart for the win!

 

The engine is probably worn out, that's why it seems smoother.
And the oil is NOT going to make the battery charge faster...

 

It could be that the thicker oil kicked out some of the existing sludge and cleaned other parts which they can move freely again

If the statement above is true, I'd change oil the next 3,000 miles just in case loose sludge is in circulation.

 

I might try the 5w-30 next time.

 

I used 10w 30 on a different car that took 5w30. It bogged the car down and was down on mpgs. Roommate did the same with his car, same thing. Slowed it down.

Posted via the PriusChat mobile app.

 

Pick your poison. Don't know what year that chart is from, but I remember it well. My owner's manuals in the past said to just pick one.

Now, with my 2016 Prius, my gas mileage has not decreased one bit after switching to 5W-30 Mobil 1. In fact, the mpg went up just slightly. I've gone through five, 500 mile tanks, and no decrease in mpg. And I feel the ICE is a bit quieter and smoother. No bogging down whatsoever. 55 or 56 mpg on each tank. AC running everyday. And PWR mode. It's all good. And I just feel better with using a slightly thicker oil. (I can always go back to the watery 0W-20. )

 

Idk, but that looks like a very old chart. Search on google I'm finding other different charts, also posted in Priuschat:
Prius 2012 - AU engine oil cap and recommended engine oil | PriusChat
The images there give 0W-20 as US spec and "please change to 0W-20 at the next oilchange if you use a heavier weight". My Dutch manual states the same, 0W-20 is recommended and 5W-30 is allowed but it needs to be changed to 0W-20 at the next oilchange.
This is for a 2011 Prius.

 

Yes, thank you. The chart above, is from 30 years ago? That's what we used when I was a young man.
For the Prius, 0W-20 is fine. But my USA owner's manual does say that thicker oil may be used if the car is driven in more severe conditions. Same with Australia? Alan posted a chart showing various viscosities? Toyota apparently recommends different viscosities for different parts of the world.

 

Keep us updated!

 

The chart indicates 5w-20 should not be used in weather that's warmer than 20F. Suprised mine has worked all this time, going to get the oil weight changed out now.

 

grid, I think that's a pretty old chart. I was just bringing up an example of the oil charts I saw when I first started driving. Many, many years ago. Maybe those aren't synthetic oils? Your 5W-20 is probably fine.

If in doubt, we can always do what Toyota says in the owner's manual. They say 0W-20 synthetic is good in all temp ranges.

 

Fake news, bring back Alex Jones!!! You owe me 5 quarts.