MellonC00

Driving from Vegas to So Cal area presents some very hilly driving conditions where you can climb some 5000ft in one long shot. I was on this drive some weeks ago Believe or not, the temps hit 116 on my way up the hill. With 5 passengers and full luggage, it was about as a tough a condition a car could face in terms of cooling needs. Obviously, I was using both electric and ICE at the same time to maintain 80 mph which seemed to be about the pace in the fast lane. (as the car climbed most cars were slowing down but I kept it at that speed to see if my car kept up). As I crested up the hill, my 450h, ever so slightly, went just a bit beyond the middle of the temperature gauge.

So I began to think, is the 0-20 standard for our car's oil the same for Minnesota and High Desert of CA and NV??? Or does the peak temperature difference doesn't matter so much for the RX's engines as it has modern computers figuring stuff out all the time. Does it matter that it never goes below freezing here where as it may go below 0 in some other parts of the country?

Olasek

Yes, peak temperatures don't matter and computers have nothing to do with this - it is because high temperatures don't impede engine start-up as far as oil is concerned.
What matters however are lowest temperatures since they may influence how car starts.
Simply follow manufacturers recommendation for your region and type of oil.

MellonC00

Well, I'd agree with you but some things are off in Lexus recommendation. In 2009, for our engine, 2GR-FE, the recommended viscosity was 5-30. Starting in 2010, it became 0-20 for the same engine.

Olasek

I don't see anything "off" here.

MellonC00

Does this mean we can 5-30 oil in our engines? From what I gather, 2GR-FE engines (which is what we have) have been the same spec since 2009. So, then I can run 5-30 also???

HKPolice

Running a thicker oil actually increases engine temps. Oil is not just used to lubricate, but also to cool areas of the engine where coolant cannot reach, such as under the pistons. A thicker oil = less cooling ability because less of it is circulating per minute.

Thicker oil also means more hydrodynamic friction which again, heats the oil & engine up more. Unless your engine is tuned with aftermarket performance parts, stick with the manufacturer recommended grade of oil.
The RX450H engine also has lower maximum output than the RX350, with higher efficiency so heat is the least of your concern.

If you're worried about coolant temps, a good cleaning of the radiator will help, coolant additives like redline water wetter might also help reduce hotspots in the coolant system but could also be snake oil.

N4TECguy

If your engine is in good condition and you do regular maintenance, it shouldn't be an issue. I live an hour south of Death Valley and use 5w-20 and 0w-20 in the vehicles I have that are designed for it. Sold my Accord at 140k, Odyssey at 150k, and both running great at the time. Using Toyota 0w-20 currently in the RX.

The real issue with 0w-20 or 5w-20 is that it isn't as forgiving as maybe a 0/5w-30. If you run it too long and it shears, instead of going from a 30wt to a 20wt, now you're going from a 20wt to a 15?10?wt. Same with fuel dilution issues, but I don't think that's a major issues in these since they are not direct injection.

If it's any consolation, some of the new Toyotas use 0w-16. I know the 2018 Camry 4cyl I carpool in, had that written on the oil cap.

afpj

There are multiple specifications you can look at for motor oil. A simple one to look at comparing 0w 20 to 5 W 30 would be the flashpoint. On mobile 1 website, Flashpoint for 0 w 20 is to 224° C (435.2 F), Flashpoint for 5w 30 is 230 (446 F). Compared to driving in the winter here in the high desert and the summer as it is now where it got up 119 degrees Fahrenheit last week, I only see at most a 20 degree difference in operating temperature of our RX 350. It typically runs at around 185 degrees in the winter but driving up the long grade from Las Vegas to Southern California, most it goes up to 205 F using ScanGauge setup. Therefore I would conclude that there is really not much difference between 0w-20 and 5w 30 regarding desert driving versus anywhere else. The primary issue would be cold start viscosity as a general rule so with 115k miles I continue to use 0w 20 without issues, as recommended by its maker. If I start noticing oil consumption issues, I may switch to a higher viscosity.

MellonC00

Excellent data points. Thank you for the measurements. I'll stick with 0w-20.

tempestv8

One of the reasons why most car manufacturers are specifying lower viscosity oils is for improved fuel economy. Lower viscosity oil = lower internal resistance for the engine when it is running.

It's a marketing ploy - sell a vehicle with slightly better fuel economy than the previous iteration or against the competition, and it becomes a consideration for the buyer, especially in times of higher fuel costs.

If you only live in a hot location where it never snows, then a slightly heavier oil (5W-30) would be perfectly fine (not to mention a lot cheaper for those on a DIY budget).

afpj

Why do you say 5w 30 is cheaper than 0w20? Wally World sells both in 5-quart jugs, mobile 1, for $22.88.
You're not talking conventional oil are you? That, in my opinion, would not be a good move for this engine spec'd out for synthetic.

tempestv8

As far as I can tell, all engine oils with 5W-30 or lower viscosity are 100% synthetic. I have yet to come across a semi synthetic or traditional mineral oil with such low viscosity. Nonetheless, regardless of whether they are synthetic or not, 5W-30 oils are cheaper than 0W-20 oils in Australia. Check out a popular oil retailer website http://www.supercheapauto.com.au and you'll see what I mean.

lexusrus

There is a NONSYNTHETIC version of 5W-30 in Mobil and others.. I know this bc my RCF per Lexus specs calls for this. Specifically calls for REGULAR NONSYNTHETIC 5W-30!!! Not synthetic!!!
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After my warranty is over I'll be using synthetic. For now, I'll have to change the oil and oil filter every 5K miles bc it's regular dino oil, not synthetic.

tempestv8

Wow, OK that's interesting. I've yet to find a non-synthetic engine oil of this viscosity range in Australia. Not sure why.

Even the Mobil1 engine oil variants sold in Australia through the official distribution channels are different to the product available in the USA. To get the USA made Mobil1, I have to use a parallel/grey importer.

As to why Lexus would recommend a non-synthetic engine oil, that's interesting, and puzzling. Why would Lexus not want a synthetic oil? To avoid engine oil leaks perhaps? The V6 motor does have a known potential oil leak issue with the timing chain cover gasket...... maybe the use of non-synthetic oil will mitigate the risk of an oil leak. To remediate the issue, it is an "engine out" type of repair, so the use of a fully synthetic engine oil could exacerbate the possibility of developing this fault, as fully synthetic oils have a tendency to "find leaks".

If I can find a conventional engine oil, I'd much rather use that, instead of fully synthetic, for the reason of avoiding oil leaks. I think fully synthetic oils are overrated for everyday suburban driving. I do change the oil myself, so I do keep an eye on the condition of the oil all the time.

afpj

Interesting what's available in Oz. I suspect synthetics are mandated due to their generally longer OCI compared to Dyno oil, thus more environmental friendly as much as oil can be.