Higher viscosity oil for motorway driving

The oil cap has 0w20 molded onto it. The US manual says that if 5w20 is used, switch back to 0w20 at the next change. So they seem very keen to use only the 0w20 oil.

 

5w30 or 0w30 would be fine.

*edit* The only negative is that you "might" see gas mileage drop slightly. I used Mobil 1 5w30 synthetic in mine for a couple of changes and I saw no difference in fuel consumption.

 

The USA owner's manual offers a similar suggestion, which they make as vague as they possibly can.

 

yes, due to CAFE.

see above.

non-CAFE countries allow for 0W20 all the way up to 20W50.

 

^ Australia for one. There the Owner's Manual shows a complete gamut of oil grades, IIRC.

 

I don't think there be much gain using 0-30 maybe a slight decrease in mpg! If your not encountering extreme driving condition such as extreme heat,towing, racing, don't see a call to switch! BTW. Good chance it will effect your emission reading too!

 

The other thing you might want to look for is ACEA A1/B1 rating which is hard to find in 0W-20 but you might find that in 0W-30 grade. I am not the expert, but that highest rating apparently goes to formulations which resist breakdown over time in the engine. The Toyota stuff seems quite good quality.

 

why would that be?

 

The larger number indicates a higher viscosity. In cold weather, and when starting the engine, a thinner oil will ease starting and flow more freely.

But, when the engine is hot, especially if you drive a constant 70 MPH, you want a thicker oil that will continue to stick to the engine parts and provide lubrication. Hence the reason to use a 0w40 instead of a 0w20.

But, the 0w40, being thicker, will probably reduce mileage, as the engine needs to work harder to splash the rods and crank through the thicker crankcase oil. This in turn may slightly affect emissions. But, it may be better for a car that's routinely driven at high speeds.

 

yeah, but he says it'll affect the "emission reading"/
meaning, like when you go to the smog test & they put a probe in the exhaust, the readings will be different than with the 0w-20 oil/
that's what I don't understand/
from my understanding it shouldn't affect this numbers at all/

 

I wonder about Toyota's motivation to specify 0W20, if it's basically to wring a bit more mpg, and engine longevity may suffer. Not sure though. Talking myself into something, lol.

 

LOL, read between the lines. have they ever claimed it increased engine longevity (besides cold start)?

 

Looks like some of those benefits can be attributed to better quality/additized lube oil, as opposed to viscosity specs. I actually do feel the Toyota brand oil is among the best quality, at least from the specs folks have posted here in the past.

I do feel there was a change in piston tolerance between Gen2 and Gen3, as engines are getting tighter. Gen2 reportedly had the tendency to pick up ~2% fuel blow-by in the oil, so I do not like to go down to 20 weight for Gen2. Gen2 we have 5k drain interval.

I almost picked up 6 quart of 5W-20 from an Oregon Gen3 Prius Chatter, so adverse to use it, is he. But I did not want to stuff it in my suit case for the flight back home.

 

that's from the australian user manual /
so obviously it's not going to hurt the engine using a heavier oil /

BION
StarCaller

 

unless you use it in too cold weather for cold starts.

in case of prius, at least the US and overseas advice overlaps (ie 0W20 is OK in most all condition). I have an engine in another toyota car where the US spec is 5W30 while overseas spec 5W30 only acceptable in winter and 10W30 or heavier is to be used in summer temps. as soon as i learned that, i started using 10W30. sadly, dealer used 5W20 a couple of times under warranty and they argued it was backspaced, (it never was). BTW, the engine developed a funny noise (when cold) after those 5W20.

 

In my area, where we have no winter it seems, I would actually feel a little more comfortable with 0W-30 or 5W-30 synthetic. But what the heck do I know.

 

since my first oil change at 1500 miles I use mobil1 0w-40/
my average at 38.000 miles is around 52mpg/


BION
StarCaller