GR Corolla/Amsoil 0w-20 oil temp questions..

[wooferocau]

As per a previous thread i started, I am using Amsoil 0w-20 in my New 2026 GR Corolla . I have just passed the 2500km mark so am now able to fully use the available rev range .

My usage..... I drive anything from casual day driving to "spirited" mountain road ( Twisty) driving....never "thrashing" it though! ........I DO NOT DO TRACK WORK/DRIVING.

Most everyone here straight up advised to use a heavy 5w-30 oil ....which i understand the reasoning behind.

From my last couple of drives in very steep mountain roads and pushing the car with ambient temps around 20-25c , the oil temps MAXED at 103c..... and averaged between 85c and 95c

My question ..... At what OIL TEMP is the AMSOIL Signature Series 0w-20 capable of handling and not falling out of grade ??

 

[ltslimjim]

You’ll find the AMSOIL Signature Series line to be very shear stable. Get an oil analysis to check for the end viscosity, but that might be skewed by any fuel presence. The AMSOIL Signature Series 0w20 is relatively “thick” for a 20 grade anyway, but those oil temps aren’t anywhere close to track days.

 

[Wheel366]

Doing a quick conversion cause you know I'm American and can't work in Celsius, I see those temps on the highway when it is warmer out and I'm not pushing it. I've seen close to 230F in my Legacy driving to FL in the summer and I wasn't worried and that was running Mobil 1 Extended Performance.

 

[wooferocau]

Doing a quick conversion cause you know I'm American and can't work in Celsius, I see those temps on the highway when it is warmer out and I'm not pushing it. I've seen close to 230F in my Legacy driving to FL in the summer and I wasn't worried and that was running Mobil 1 Extended Performance.

what weight ?

 

[DCDG]

High quality modern synthetic 0W-20 will handle short bursts of 230° without an issue you sure won't have to worry about condensation.

 

[mitsuman47]

While those temps seem “fine”, no one here can tell you at what temperature a 20 grade oil will have insufficient viscosity to protect your engine. None of us have your engine and the equipment to test and measure this for you. Especially when the only temp we have is of the sump (I’m making an assumption that your gauge is showing the sump temp).

Different parts of your engine can have dramatically different temperatures, and the oil in those areas will increase in temp and experience a reduction in viscosity.

A 20 grade was likely chosen for EPA reasons (at least IMO). Since a higher viscosity is almost always better than less when discussing wear, it is a pretty easy choice to bump the operational viscosity up a grade.

Consider the increase in viscosity as giving yourself a bit of headroom.

 

[Japanese]

From my last couple of drives in very steep mountain roads and pushing the car with ambient temps around 20-25°C, the oil temps MAXED at 103°C... and averaged between 85°C and 95°C.

Those look normal oil temp. to me, especially if the car was pushed a bit. Nobody can answer (except probably Amsoil) if the oil shears or stays in grade. I assume the oil stays stable since the temperatures are not abnormal and also is a high end Amsoil 100% synthetic oil.

However, I would refrain from spirited driving until I reach about 10 000 km or when I'm completely done with the break-in process (shown in UOA), or until I move to 5W-30 grade. We usually say here -"Better safe than sorry!"

How long will be this current OCI and how many km overall are planning to drive with 0W-20 oil before you go to 5W-30?

 

[Wheel366]

what weight ?

0W-20.

 

[RallyXaDSM]

A 20 grade was likely chosen for EPA reasons (at least IMO).

Toyota actually only "recommends" 0W20 for these engines in every market they're sold, including markets like Japan and Mexico where the GR Yaris was available long before the US market got the GRC. It's one of those odd outliers from what is otherwise usually the case.

 

[wooferocau]

Toyota actually only "recommends" 0W20 for these engines in every market they're sold, including markets like Japan and Mexico where the GR Yaris was available long before the US market got the GRC. It's one of those odd outliers from what is otherwise usually the case.

This is the aspect that has me most curious....WHY do they ONLY spec 0w-20 ?? and no option for other weight options ??

 

[Japanese]

Because the most important property of an oil is its flow. Also, if the oil optimum working temp. is kept in range and the oil is changed on time - there is nothing to worry about.

Your oil temp. are perfectly fine. People usually start to worry if their oil temp. gets to 220°C and over. Oils are tested at 150°C as well - that's how their HTHS property is established.

 

[rstsco]

You'd have to be trying a lot harder than spirited-driving to even get close to breaking the back of Amsoil Signature Series 0W-20. I ran it in my 2022 Audi, and tnen in my 2025 Pilot until the last oil change at 13k miles on the odometer, when I made the switch to HPL Premium Plus PCMO (personal reasons, not that I didn't trust the oil).

Where you live, it doesn't look like temps get very cold in your winter. You might want to consider switching to a 5W-20, as the NOACK Volatility is 5.8 vs their 0W-20 at 8.5. Either way, you have nothing to worry about.

 

[wooferocau]

Where you live, it doesn't look like temps get very cold in your winter.

Temps do get down to -10c here in winter..

 

[DCDG]

Because the most important property of an oil is its flow. Also, if the oil optimum working temp. is kept in range and the oil is changed on time - there is nothing to worry about.

Your oil temp. are perfectly fine. People usually start to worry if their oil temp. gets to 220°C and over. Oils are tested at 150°C as well - that's how their HTHS property is established.

Very good way of putting it. Most fail to recognize this.

 

[Japanese]

Very good way of putting it. Most fail to recognize this.

I ment above 120°C oil temp., not 220°C. Cannot edit my post yet.

 

[wooferocau]

I ment above 120°C oil temp., not 220°C. Cannot edit my post yet.

I gathered that's what you meant

 

[randomhero439]

I wouldn't think twice about oil temperature unless you are regularly exceeding 130C (266F). This is where oil and additives start to break down rapidly.

You state 103C oil temp... this is like normal operating temperature. Drive harder

 

[4wd]

Temps do get down to -10c here in winter..

But wrong time of year

 

[ltslimjim]

Temps do get down to -10c here in winter..

You can ignore 0w if desired in that case. For OTS oils, I still prefer 0w when possible, but in this case AMSOIL Signature Series 5w20 might be an even better choice as @rstsco indicated with its superior low volatility, but we could be splitting hairs here and it gets into another discussion regarding 0w vs non-0w.

Side note: IMO that’s an argument for OTS oils and their differences in base oil blends and overall formulation changes between winter grade alone. This isn’t an issue for boutique oils like Amsoil SS, as they aren’t made to a “lower the price point” for themselves at any cost; even at the expense of the end product performance. OTS synthetics it is more common, so 0w oils could have more preferred ingredients basically. When shopping boutique, go with grade desired without that concern.

End of rant…

 

[MLRTYME]

103 celsius is nothing and the Amsoil 0W20 will handle that no problem. Going to a higher viscosity may increase temps as thicker oil retains heat more. Amsoil is great oil and I would just run the 0W20 without any worries.