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

Factory recommendation of 0W-20 -- for those who don't want to experiment with different viscosities. But I really like the 5W-30 Mobil 1. I'm sticking with it.

And what happen to that BuickGM poster???? He disappeared.

 

You should delete it because the post doesn't state that its out of date, a random lurker looking for info on here may just use it as a guide and follow it.

 

Sorry, too late to delete. I think Alan Clarke posted a more current chart.

Somebody wanted to know how my gas mileage is doing with the Mobil 5W-30? Doesn't seem to have affected the mpg at all. Here is another 500 mile tank. (the 4th or 5th?) I actually filled up at 504 miles, and put in 9 gallons exactly. Came out to 56 mpg calculated. (the DTE showed 60 miles left, plus some fumes ). AC always on, and in PWR mode. I can't complain about 56. I'll check the mpg again in a couple years.....
Just Drive It.

 

The dealer on your country recomends 5w40 because of hot climate, 1st owner of my prius used 10w40 liqui moly, i did on 10w40 close to 6k km then switched on 0w20 idemitsu and I get 8% less.

 

This is an old thread but interesting. It may also be off topic for me as I have a gen2 2007 Prius with 120k miles. The recommended oil for my car is SAE 5W-30 but I live in Florida and it gets very hot so, I was wondering if switching to a 5W-40 full synthetic or high mileage would be more beneficial for me during the summer months where is often is above 95-100 degrees F. Also, a lot of people here mention their favorite oil is Mobil 1 but what’s odd is the bottle doesn’t have the SAE wording. Thoughts?

 

0w-20 or 0w-16 oil? manual conflicts | Page 6 | PriusChat

I've done oil pressure testing on my 3rd gen Prius and fend that it gets up to 55 PSI at 3,000 RPMs and 160 f engine temp. 0w40 seems like the right oil for that engine. I used to use 5W-40 in my second gen Prius. I will tell you that 15w50 gives you oil pressures so astronomically high that it blows the oil sensor out of the back of the engine. So there is a limit on this. You won't find me using 0w20 and these engines and you won't find me using 15w50. Either. Zero base or 5 base and 30 or 40 for summer is where you want to be

 

I would add to @douglasjre's excellent advice that 'real oil pressure' is the way to go ... not a darn idiot light.

Another trick that I learned 'in the field' is filling to 3/4th level leads to a slight but measurable efficiency improvement in most ICE engines. This is not a trivial technique when refilling after an oil change and leads to a partially empty oil container.

My speculation is the slightly reduced oil level avoids any 'splash' interference with the crank and piston rods. It may also lead to a slightly higher and lower viscosity due to the lower oil pool mass.

GOOD LUCK!

Bob Wilson

 

When I put the spec'd 4.2 liters in our '10 after an oil drain and filter replacement, and leave the oil level check till after a drive or two, it's invariably about 1/4" below the top mark (equates to about a cup). I think it may be due to my DIY technique, raising the front quite high, versus a pro shop just raising the car on a lift (keeping it level). It also seems it'll be a slightly more complete oil change.

Anyways, it's fine by me, have that same hunch, that a slightly lower oil level means less splash.