Chosen Oil Viscosity...?

HTHS makes a big difference in the main bearing wear. That's why GM revised back to 0w-40 instead of 0w20 on their pickup Trucks.
Toyota engines are not known to have main bearing problems unlike BMW, VW, or GM.

To compensate the thinner oil, most 0w-8 oil contains high amount of antiwear especially Borons. So, do not mess around with adding oil additives that mess the balance and optimum ratios of the additives and detergent.

Toyota engine prones to piston rings clogging more. Viscousity Modifier (VM) % in 0w-40 or 0w-30 is higher than 0w20. VM tends to degrade faster and create deposit more.

So choosing the oil viscousity depends where and how we use the car. Using 0w-30 or thicker is suitable in warmer climate or if we do towing or live in the mountains.

 

I'm just going to point out that GM's switch to 0W-40 is only because of the defective crank journals. If they had been machined properly, GM would never have switched to 0W-40 for those engines. If you have one of those engines and it's been damaged bad enough to warrant replacement, the new engine with a correct crankshaft will be specced right back to 0W-20.



Personally, I have absolutely zero worries running 0W-16 in my gen5. I wouldn't have had any problems even if Toyota had specced 0W-8 like the same engine in the Corolla. As long as the engine is designed with the thin oil in mind, the engine parts are made of quality materials, and the manufacturing process means the finished product meets or exceeds the design specs, I'm fine. I don't know how confident I'd be with a GM, Ford, BMW, MB, or Audi that specced 0W-16 or 0W-8, but I don't worry about Toyota. I'll just do my 6m/5k mile changes and sleep well at night. The only thing I could wish different would be if Valvoline made Restore & Protect in 0W-16 and 0W-8.

 

Keep in mind that the antiwear/extreme pressure/friction modifier (AW/EP/FM) additives are for the valvetrain and cylinders, which do or may operate in the boundary-lubrication regime. For bearings, you need a minimum HTHS viscosity to achieve a minimum oil-film thickness (MOFT), as they operate in the hydrodynamic-lubrication region. For the boundary-lubrication region, both the base-oil viscosity and AW/EP/FM additives are important.

Boron additives these days are almost always dispersants, not antiwear additives, even though a while back some oils experimented with boron antiwear additives. Toyota has been using a lot of boron dispersants in their genuine engine oils (TGMO) after its sludge problem. ExxonMobil makes the TGMO in the US.

 

Is any non-Japanese brand recommending 0w16 or 0w8?

 

Yes.

ACEA oil sequences 2023—Light-duty engines—ACEA—European Automobile Manufacturers’ Association

 

The API has standards for 0w16. That doesn't mean Ford or GM is calling for its use in owner's manuals.

 

Just as ILSAC is a consortium of American and Japanese car OEMs, ACEA is a consortium of Euro car OEMs. ACEA did not have SAE 0W-20 until recently, but now, it is common with Euro OEMs. If SAE 0W-16 is in ACEA now, some Euro OEMs will adopt it in the near future, as ACEA is nothing but a governing body of Euro OEMs.

 

That is right, some Ford engines consume oil if we use higher viscousity because the cylinder wall cross hatch patten is designed for thinner oil. I also prefer whatever recommended by manufacturer for most engines application. The only thing to prevent me using 0W-8 oil is pricing and aftermarket availability. If I can find it with reasonable price for newest Camry, Yaris, or Crown, 0W-8 is the one to go.

I do not know if Toyota still have engines with chronic oil consumption problems like 2010-2014 Prius/PriusV/Corolla hybird engines. I found that thicker oil does not help on those engines. Only more frequent oil changes (5-8k miles) with high quality full synthetic oil helps. I think GTL Pennzoil, Shell, Quaker State Ultra Platinum helps because of more robust base stock that needs less additives to fullfill DexosD or Dexos1 gen3 requirement or higher.

 

Yes, those problems happen because the piston oiling rings get clogged up with sludge/carbon. Changing the viscosity won't help that problem at all. If anything, it might make it a bit worse. The only prevention is more frequent oil changes(6m/5k mile for naturally aspirated and 4m/3k miles for engines with oil-cooled turbochargers or superchargers). And the only solution once it's happened is to either free up the rings or replace them(usually not cost-effective). And if you don't catch it in time and the cylinder walls get scored, your engine block is toast.

There weren't great solutions for freeing rings non-invasively until Valvoline Restore & Protect hit the market a couple years ago. You can use a powerful engine cleaner(way, way more powerful than the things you can find on the shelf like SeaFoam), but you always run the risk of damaging your gaskets and seals with those aggressive products. VRP seems to help free up the rings over time without doing any damage.

I'm using Toyota 0W-16 only because VRP doesn't come in that viscosity. The day it does, I'm switching over.

 

As for 0W-8 cost, you can get TGMO for as low as $8.28/quart from Toyota dealerships during sales if you shop around. Or you can get Mobil 1 for $28 for a 5qt jug($5.60/quart) from your local Walmart.

For contrast, 0W-20 Mobil 1 is currently $25 for a 5qt jug at Walmart($5/qt), TGMO would be $2.71/qt at max discount, and VRP is $30 for 5qt at Walmart($6/qt).