Why would you run 0w-20 in a desert (hot) climate? (yet another oil thread)

i have a V6 RAV4 and I spent a lot if time on RAV4World that has a number of canadian members and that car/engine combo never ever was approved for anything else than 5W30. the chart shows otherwise.

 

There was another older thread where a lube expert was saying that he felt the Toyota 0W-20 was superior for MPG because the VI was higher than any other oil (Prius c thread IIRC). So I suppose we'd have to keep VI constant in your proposed test. But sounds to me like Toyota really wants the 0W for low temp engine protection, so why do you care about putting an oil heavier than Toyota wants in there for engine life?

Apologies by the way I do not own a Gen3 but I am just coming to grips with the fact that Toyota seems to be "mandating" the 0W for newer Toyotas.

 

Toyo's 0W-20 all I've ever used, fwiw. Dirt-cheap at the parts dept.

 

I find it useful to think about oil in two parts:

Is a 30 weight oil an advantage over 20 weight in the desert ? Since you do not expect to run the engine at temperatures greater than the usual driver, the answer is no. So use the less viscous oil, as Toyota recommends.

Is a 5w oil a disadvantage over 0w in the desert ? Probably not, since I'm willing to guess that the viscosity of a 5w at 60F is already thinner than a 0w at 30F

Now on to your real question, whether to waste your stock of 5w-30.
If it is synthetic, I would be tempted to use it 50:50 with 0w-20

 

Okay, so lets bring in some of the real world into the mix. Now, I recently acquired a JDM 2012 Toyota Prius with 17" rims and 75,000 kms on the odo. I ran it for 3000 kms on the previous oil (no idea what the seller was using) averaging 700 kms over 34 litres of refill for 90% city driving. That's 21 km/l or 49 mpg which is a phenomenal achievement! Now, I figured lets not push the existing oil too much, and I ended up changing the oil to a fully synthetic Liqui Moly 5w - 30 variant (succumbing to the its-hot-where-I-live-and-0w20-is-too-bulemic) after several bouts of intense forum research (local knowledge on the Atkinson 4 is virtually zero and everyone has a different opinion).
Now, I haven't quite gone a full tank yet, but the digital read out (which has been amazingly accurate thus far) displays 17.1 km/l, or 40 mpg, regardless of how frugally I drive (and I am especially careful with the throttle). There is no change in the vehicle or driving habits at all. Our ambient temperatures are 32C to 40C constant in the day (I would describe this as California-like hot) and perhaps 20C by night. That drop in mpg seems quite serious to me as economy is at the epicenter of this vehicle. The caveat here is that I'm trusting the dash read-out, which I must reiterate has been extremely accurate calculating km/l-mpg for the 3000 kms I drove the car. The drop in mpg, I would deduce, is the direct result of the viscosity of the oil!
The big question now is, should I give it a couple of tanks worth of cycle or just source a TGMO 0w-20 and change?

 

Had to Google this, lol: TGMO = Toyota Genuine Motor Oil.

It's a little surprising that your dash displayed fuel economy is accurate; maybe Toyota sets it up differently in other parts of the world. In North America it's very regularly optimistic, in my experience around 7.5%.

With your climate I wouldn't be in a rush to switch back to 0W20, might even stick with 5W30. Just give the fuel economy some time. If it's really troubling, try 5W20 next time, see if that helps?

Welcome, by the way.

 

TBT was yesterday.....

The original question was basically in three parts:
1. Whether or not to use a case of pre-existing 05W30 in a G3 (I would)
2. WHY Toyota specs thinner oil for Priuses (fuel economy)
3. ....and if the answer to the first two questions would differ in a hotter or colder climate (a wobbler.)

I've seen the battles rage back and forth and I remain unconvinced that it makes much of a difference to somebody who regularly checks their oil, and operates in a moderate climate.

My thoughts (Current Street Value < $0.02USD)

1. If there were a meaningful fuel economy delta, we would know approximately what that value is for G3s by now. I'll specuguess that it's less than 2MPG.
2. If your OCI is 10,000 miles then I'd stick with synthetic, use 0W20 and check my oil level every other tank. My company car is out of warranty, and they use a 5,000 mile OCI, and I think they use the cheapest 5W30 they can find. So far (96,000 miles) I can't detect any difference and my real world MPG hovers in the 46-50 range. TIFWIW.
3. Climate matters a little bit, but only in the extremes and only when you start the ICE in cold weather. Priuses have a cooling system. I think that once the engine reached normal operating temperature it will be the same temperature in the Mojave Desert as it is in Anchorage Alaska....except when the temperature is cold enough to require a block heater....so the viscosity should be pretty much the same for those people who live in 90-percent of the country.
Running thicker oil in the desert buys you no additional protection. The OEM oil is no factor for extremely cold climates, but you may want to consider a block heater and/or a garage if you're going to club up to 5W30.

Takeaway: It is what it was.
Use OEM spec oil.
If you DIY, you can club up to 5w30 IMHO. If you're burning oil at 1q/1000 miles you can put jst about anything you want into it (I'd try a high mileage blend 5w30 first.)

CHECKING your oil level (which most people do not) will do more to affect your engine life than just about anything else.
If there was as much attention to detail and argument about that as there is about viscosity and brand bashing, then Prius Oil Use would fall dramatically.

BT

 

This is an older thread, but I always enjoy a good oil discussion. And I would like to send my compliments to ETC(SS). Thank you sir. I have read many of your comments in various forums, and you always have a very knowledgeable, practical, and "commonsense" approach in your replies. You are my favorite poster, and I hope you keep up the great work.

After much debate (with myself) and reading numerous articles, I am going to stay with the factory recommended 0W-20 synthetic oil. I be sure to check my oil level twice a month, and I change it every 5000 miles. This is due to many short trips, and driving through areas that can get very hot. Might not be necessary, but it just make me feel better to change it a little more often. Cheap insurance, as I call it.

Thanks for a great discussion.

 

Not true. It's always at operating temp 190f. In fact it may run just to warm the cats to meets its number 1 mission which is low emissions. And a cold engine has higher emissions and is much less effecient than a cold motor.
Toyota recommends 0-20 as it may help a tiny bit to meet there claim of mileage. That's the only reason.
If I owned a G3 and lived in a hot climate I would run 5-30.

 

The owners manual state's at the end of the oil section it may be beneficial to use heavier oil for fast or hard miles, I can only assume this would include hot climate

Posted via the PriusChat mobile app.

 

Split the difference. Use two quarts of what you have every oil change. Top off the rest you need with the 0w oil. Then everyone here willl be happy. Wait, not everyone. There will be that one guy who balks at mixing weights. Who cares. It's freaking oil. Get it close, start the car and drive it. People act like oil will miraculously add a half a million miles to our Prius engine when most toss a head gasket at around half that. Others act like using the wrong oil will make the magnetic poles of the earth shift.

The owners manual states.........blah blah blah. Toss that manual written by lawyers in the dumpster. Remove all the safety warnings and all you would have left is a coloring book. Right on the oil cap under the hood it says what oil to use, so use that or something close.

 

I agree no big deal mixing weights, brands whatever it's going to be better than what comes out.
As long as it's got a new filter and at the correct level which is 3.5 quarts with a new filter.

I use really good oil but I bought the car new and have a bigger investement in it than say someone who bought it used with 100k miles on it. I treat the trans the same way but as far as the trans is concerned it could care less what brand fluid you use as long as it's dex 6,

It's not rocket science it really isn't.

 

0W-40 Mobil 1. Average 50 mpg.