0w-8 vs 0w-30

Pennzoil motor oil
W

Wiremanjon

Joined
Aug 7, 2024
Messages
12
So I’m no expert in oils but I’ve learned a little bit over the past few years. I’m trying to reconcile whether my Toyota Camry could safely run 0w-30 motor oil without any detrimental effects of the added viscosity. If I understand correctly 0 weight oil is thicker when cold than 30 weight oil at operating temperature? If this is true, and if my used oil analysis of the 0w-8 proves it to be inadequate to prevent wear. Would the engine operate normally if I bumped it up to 0w-30? I mean the winter number is staying to same, it’s only the 2nd number that’s going up. If I understand correctly the 2nd number is not actually the weight of the oil but the protective characteristics of 30 weight at 100 degrees Celsius?
 
Toyotas that run 0w-8 can use up to 10w-30. This is from a different model with 1 cylinder less but clearances are identical since it's the same new engine architecture. But the a25a has remain unchanged clearance wise since it was introduced about 7 years ago and those use 0w-16 to 15w-40. It was tested to not have insufficient oil pressure with 0w-8 and since the pump is computer controlled it can always increase the amount it has to generate so it doesn't throw a rod. That and making sure the surface on the bearings are precise which is what allows 0w-8 in the first place. It was discussed before but I don't know the thread to link.

Screenshot 2025-02-03 143555.webp


This is for the a25a.
a25a 0w-16-15w-40-2.webp
 
Last edited:
Wiremanjon said:
So I’m no expert in oils but I’ve learned a little bit over the past few years. I’m trying to reconcile whether my Toyota Camry could safely run 0w-30 motor oil without any detrimental effects of the added viscosity. If I understand correctly 0 weight oil is thicker when cold than 30 weight oil at operating temperature? If this is true, and if my used oil analysis of the 0w-8 proves it to be inadequate to prevent wear. Would the engine operate normally if I bumped it up to 0w-30? I mean the winter number is staying to same, it’s only the 2nd number that’s going up. If I understand correctly the 2nd number is not actually the weight of the oil but the protective characteristics of 30 weight at 100 degrees Celsius?
Click to expand...
How many people have posted this over the years? There are no "0 weight" oils, if it is a 0W-8 grade then it is an 8-grade oil. Also not a weight. It acts as an 8-grade, never the mythical "0 weight". A 30-grade on the other hand acts like a 30-grade, all day long.

Winter rating is separate from the operating viscosity. And yes the engine will operate normally with a 30-grade.
 
Wiremanjon said:
So I’m no expert in oils but I’ve learned a little bit over the past few years. I’m trying to reconcile whether my Toyota Camry could safely run 0w-30 motor oil without any detrimental effects of the added viscosity. If I understand correctly 0 weight oil is thicker when cold than 30 weight oil at operating temperature? If this is true, and if my used oil analysis of the 0w-8 proves it to be inadequate to prevent wear. Would the engine operate normally if I bumped it up to 0w-30? I mean the winter number is staying to same, it’s only the 2nd number that’s going up. If I understand correctly the 2nd number is not actually the weight of the oil but the protective characteristics of 30 weight at 100 degrees Celsius?
Click to expand...
I would wear a helmet, preferably one with Kevlar protection. When the engine explodes due to 0W30, you don't want a flying rod bearing to hit your head.
 
Wiremanjon said:
So I’m no expert in oils but I’ve learned a little bit over the past few years. I’m trying to reconcile whether my Toyota Camry could safely run 0w-30 motor oil without any detrimental effects of the added viscosity. If I understand correctly 0 weight oil is thicker when cold than 30 weight oil at operating temperature? If this is true, and if my used oil analysis of the 0w-8 proves it to be inadequate to prevent wear. Would the engine operate normally if I bumped it up to 0w-30? I mean the winter number is staying to same, it’s only the 2nd number that’s going up. If I understand correctly the 2nd number is not actually the weight of the oil but the protective characteristics of 30 weight at 100 degrees Celsius?
Click to expand...

If the 0W-8 is proven by uoa to be insufficient, you need a rebuild. That's the danger of running thin oil, it works well without symptoms until it doesn't.
 
Can you show your lab analysis. If it's a brand new engine the break in metals like iron and others will be high naturally so 0w-8 can't be blamed too fast though you can still use thicker now.
 
Jetronic said:
If the 0W-8 is proven by uoa to be insufficient, you need a rebuild. That's the danger of running thin oil, it works well without symptoms until it doesn't.
Click to expand...
Running ultra thin requires everything be perfect. Coatings and bearing tolerances at 20 microns iirc makes it possible. Not every engine will be perfect and not every defect is caught. But extra viscosity can band aid slightly out of spec coatings or tolerances as long as it isn't too much and make an engine that might be wearing too much not wear much anymore and stay that way.

However this seems like a break in oil change so metals will be high.


Clearances if anyone is interested.
http://zatonevkredit.ru/repair_manuals/raw_content/AWH2bax9U9h2CeTmXMJZ
 
SC Maintenance said:
Isn't it the same A25A-FXS engine they have been using since 2018?
Click to expand...
The same.

The most paradoxical engine design in history apparently. One can’t use thinner oils because it’ll wear out prematurely. But one also can’t use thicker oils because the ECU and oil pump will not tolerate it. So we’re just left with use no oil I guess.
 
ATex7239 said:
The same.

The most paradoxical engine design in history apparently. One can’t use thinner oils because it’ll wear out prematurely. But one also can’t use thicker oils because the ECU and oil pump will not tolerate it. So we’re just left with use no oil I guess.
Click to expand...
Is that the electric oil pump?
 
It’s a 2025 engine. I just wonder about the various things they may have changed to accommodate the thin oil. Variable valve timing, oil pump pressures and things like that. Toyota always seems to speak with forked tongues. You can used 0w-16 for one oil change if you can’t find 0w-8 but you must go back to 0w-8 at the next oil change. Then they say if you use your car under high temperature or extreme conditions a thicker oil viscosity may help protect your engine better. Talk about misleading statements.
 
Wiremanjon said:
It’s a 2025 engine. I just wonder about the various things they may have changed to accommodate the thin oil. Variable valve timing, oil pump pressures and things like that. Toyota always seems to speak with forked tongues. You can used 0w-16 for one oil change if you can’t find 0w-8 but you must go back to 0w-8 at the next oil change. Then they say if you use your car under high temperature or extreme conditions a thicker oil viscosity may help protect your engine better. Talk about misleading statements.
Click to expand...
Or if you move your engine to Australia you can use totally different oils. Must be the Coriolis effect messing with the oil pump.
 
Wiremanjon said:
It’s a 2025 engine. I just wonder about the various things they may have changed to accommodate the thin oil. Variable valve timing, oil pump pressures and things like that. Toyota always seems to speak with forked tongues. You can used 0w-16 for one oil change if you can’t find 0w-8 but you must go back to 0w-8 at the next oil change. Then they say if you use your car under high temperature or extreme conditions a thicker oil viscosity may help protect your engine better. Talk about misleading statements.
Click to expand...
Moronic bean counter epa guidelines. Read this post I made and click the document that's meant for manufacturers like Toyota and others. In summary they can't recommend what they didn't test with but they can with some minor exceptions but still can't recommend it but can... You can use 30 grade all day no matter the odo.

JavierH19

Post in thread '0W-8 in 2026 Toyota Prius'

JoeF said:
I'm impressed. The page from the owners manual explains more about oil than any owners manual I've ever seen, and OK's the use of .... even that "heavy" 10w30 oil 😎, and explains that it may be more difficult to start when the temperature is below zero.
I'm used to seeing the implied threat of complete engine failure if you don't use the oil spec'd by the manufacturer and labeled on the filler cap.
Click to expand...
Toyotas and other brands like nissans, kias/hyundai, mitsubishi and others all say you can use many more grades in the exact same engine sold here in the US but they can't say to use...
  • Like
  • Helpful
 
You must log in or register to reply here.

Similar threads

M
What's the downside to using 0W-30 vs 5W-30?
2 3
Replies
46
Views
2K
mojoe
H
Best 0W-20 Full Synthetic Oil?
3 4 5
Replies
82
Views
6K
tired
G
Direct Injection, Fuel Dilution, & Viscosity
2
Replies
32
Views
3K
Propflux01
L
Rationale for deviating from BMW recommended oil specs & service intervals
2
Replies
23
Views
2K
altaylar
S
Genesis 0W-30 Vs 5w-30
3 4 5
Replies
92
Views
5K
ARB1977
Back
Top Bottom