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Anyone Running 0-40w oil? Im at 170K and towing a 4500# travel trailer and would like to go heavier than the 0-20W or 5-30W wondering if anyone willing to share their experience. Im in southwest so temperture extremes do exist. thanks in advance
... direct from Toyota / Lexus Engineering ... the 1UR-FE Engine (Lexus GX460 V8) Owner's Manual (non-US Market) unfiltered by government CAFE regulation ... so for your climate, running at least 5w-30 would be recommended. With towing ... at least 15w-40. For me in the Seattle climate ... 5w-30 all year round since 2019 (purchased new).
... direct from Toyota / Lexus Engineering ... the 1UR-FE Engine (Lexus GX460 V8) Owner's Manual (non-US Market) unfiltered by government CAFE regulation ... so for your climate, running at least 5w-30 would be recommended. With towing ... at least 15w-40. For me in the Seattle climate ... 5w-30 all year round since 2019 (purchased new).
have you done a UOA with these alternative oils? Curious as to what you found.
Anyone Running 0-40w oil? Im at 170K and towing a 4500# travel trailer and would like to go heavier than the 0-20W or 5-30W wondering if anyone willing to share their experience. Im in southwest so temperture extremes do exist. thanks in advance
No, but towing 4500# in the Southwest USA I personally would run a synthetic 0W-40/5W-40 without a second thought.
The non-US owners manual that ASE posted shows the 1UR-FE is tolerant to wide range of viscosities.
have you done a UOA with these alternative oils? Curious as to what you found.
^ ... "alternative oils" ? How are these alternative ? ... why the concern when recommended by Toyota / Lexus engineering ? ... I would be more concerned using the CAFE Standard imposed 0w-20 especially in your climate.
have you done a UOA with these alternative oils? Curious as to what you found.
I wouldn't do 0W-40. I was using 5W-30 but went back to 0W-20. If you watch one of Motor Oil Geeks most recent videos, he shows that the larger delta between winter and operating viscosities, the faster they shear and break down. You'll find every opinion under the sun to be paranoid about your oil, but there are many GX examples that are running over a decade with 0W-20. Some people live in the past and can't accept that formulas improve and thicker oil doesn't necessarily mean less wear. There are other factors involved. Be a sheep like me!
I wouldn't do 0W-40. I was using 5W-30 but went back to 0W-20. If you watch one of Motor Oil Geeks most recent videos, he shows that the larger delta between winter and operating viscosities, the faster they shear and break down. You'll find every opinion under the sun to be paranoid about your oil, but there are many GX examples that are running over a decade with 0W-20. Some people live in the past and can't accept that formulas improve and thicker oil doesn't necessarily mean less wear. There are other factors involved. Be a sheep like me!
... why not just follow the Toyota / Lexus recommendation per your climate ? I think they know a little more about this subject specific to this engine that any other resource. Following government imposed regulatory standards ... that's what sheep do ... in addition to never ever changing their oil until the recommended 10,000 mile interval.
I wouldn't do 0W-40. I was using 5W-30 but went back to 0W-20. If you watch one of Motor Oil Geeks most recent videos, he shows that the larger delta between winter and operating viscosities, the faster they shear and break down. You'll find every opinion under the sun to be paranoid about your oil, but there are many GX examples that are running over a decade with 0W-20. Some people live in the past and can't accept that formulas improve and thicker oil doesn't necessarily mean less wear. There are other factors involved. Be a sheep like me!
While generally accurate, it’s a generalization regarding the viscosity spread making oils more shear prone.
Some 5W-40s are less shear prone than some 5W-30s or 0W-30s for example.
We’ve all known the 90 year old drinker/smoker, that doesn’t mean that lifestyle will suit everyone so well.
Same goes for the universal 0W-20 crowd, just because one GX went 500K or whatever on 0W-20 doesn’t mean the guy towing 4500 lbs through Phoenix, AZ in the dead of summer will be so lucky.
Viscosity should not be one size fits all deal, and IMO anyone that argue it does doesn’t really understand the topic.
Anyone Running 0-40w oil? Im at 170K and towing a 4500# travel trailer and would like to go heavier than the 0-20W or 5-30W wondering if anyone willing to share their experience. Im in southwest so temperture extremes do exist. thanks in advance
If you are looking for permission from Toyota I think ASE has posted their blessings. Do note that recent guidance had changed and those manuals have also changed to 0w20 as well in select global markets for the tail end of the j150s life.
Clearances are the spaces between parts, tolerances are the allowed amount of variation from the spec'd clearance. Mass produced automotive engines generally all have pretty similar clearances, regardless of grade spec'd. Where things change is when we get down to thinner oil grades like 0W-20, 0W-12, and 0W-8 where the MOFT (abbreviation) just isn't there with ultra thin oils, so the solution is to increase the bearing width, to increase its load carrying capacity and provide a larger film over which the load is spread. This increases friction of course and as a fact increased wear, but the reasoning here is that the increase in friction here is less than the overall savings by going with the thinner oil when looked at as a whole as a mfg and their expected program objectives. This was heavily experimented with in Japan long before it made its way to North America.
The myth of 0w20 being inadequate to the point of guaranteed engine failure is just a myth, just like using 20w50 in all ambient temperatures is the best protection for engines regardless of ambient temperatures. Whether it produces increased wear though is not.
The debate if anything for the niche oil community then becomes what are the owners objectives, how do they differ from Toyota's, and what data points/issues are they facing that their baseline 0w20 is falling short in? It may well be cost, anticipated ambient temperatures, uoa trending high in select boxes, or duty cycle. This is also before we address the other big thing which are approvals, ie api sp/sq vs say mb 229.7x or vw 508.
Last edited by Framestead; Feb 28, 2026 at 06:20 PM.
Startup Protection: Approximately 75% of engine wear occurs during cold starts. 0W oils are designed to flow faster at low temperatures, reaching critical components up to 40% faster than 5W oils in cold conditions. This rapid lubrication reduces metal-on-metal friction during the first seconds of operation.
Operating Temperature Stability: Once an engine reaches its normal operating temperature (typically 100°C), both 0W-20 and 5W-20 oils behave identically as "20-weight" oils. They provide the same film strength and protection during normal driving.
High-Temperature Caveats: Some specialized tests suggest that under extreme heat or heavy towing, a thicker oil (like 5W-30) may maintain a 50% thicker oil film than 0W-20, potentially reducing wear by 22% in severe service conditions. However, this compares a 20-weight oil to a 30-weight oil, rather than 0W vs. 5W of the same operating weight.
Manufacturing Standards: 0W oils typically require higher-purity synthetic base stocks (Group III or IV) to achieve their low-temperature flow ratings, making them inherently more resistant to sludge and evaporation than some semi-synthetic 5W formulations.
Factors That Influence Wear More Than "0W vs 5W"
Additive Packages: Wear protection is heavily dependent on the chemical additives (like molybdenum or ZDDP) rather than just the base viscosity.
Engine Design: Modern engines are built with tighter tolerances (0.001"–0.002") specifically designed for low-viscosity 0W oils. Using a thicker oil than recommended can actually cause "hydraulic lag" in components like Variable Valve Timing (VVT) systems.
Climate: The distinction between 0W and 5W only becomes significant in extreme cold (below -25°F / -32°C). In temperate climates, the difference in startup flow is often too small to measure in terms of real-world wear.
CCN is wrong about the variable oil pumps being tuned differently in other markets.
Just look at any viscosity curve and compare a 0W-16 @ 50 degrees F versus a 20W-50 @ 100 deg F.
0W-16 @ 50 deg F:
15W-50 @ 100 deg F:
Even engines run on very thin oils still have to deal with high viscosities during warm up.
CCN is wrong about the variable oil pumps being tuned differently in other markets.
Chart aside, with all due respect I'd need to see documentation showing that the tuning is the same in other markets before I accept this as gospel. Ahmed is quite thorough, and I have a hard time swallowing that he would simply spout off a claim like this without having researched it first.
Chart aside, with all due respect I'd need to see documentation showing that the tuning is the same in other markets before I accept this as gospel. Ahmed is quite thorough, and I have a hard time swallowing that he would simply spout off a claim like this without having researched it first.
Ahmed isn't thorough at all when it comes to lubrication, IMO.
Love his channel and would defer to him on many things, but not this or engine theory.
I posted those charts to illustrate that all engines are exposed to a wide range of operating viscosities, Mobil 1 0W-16 is thicker on a 50 degree F cold start than Mobil 1 15W-50 is on a 100 degree F cold start.
In light of this, it's not a reasonable conclusion that Toyota alters oil pump logic based on region.
It's basic viscosity physics that variable displacement pumps are "self-correcting" to an extent.
If you put thicker oil in, or start on a colder day, the resistance (pressure) increases, and the pump's internal feedback mechanism (or the ECU's solenoid) naturally adjusts the displacement to reach the target pressure.
This happens automatically without needing a "market-specific" map.
Toyota likely uses a single, global software map that is sophisticated enough to handle all all range of viscosities the engines will ever encounter; and in the US conditions range from Fairbanks, AK to Death Valley, CA which results in very different viscosities (due to temperatures) even with the same exact motor oil.
Viscosity is very dynamic.
Ahmed is quite thorough, and I have a hard time swallowing that he would simply spout off a claim like this without having researched it first.
Ahmed is wrong on this. First off, not many Toyota's have variable oil pumps (the GX460 does not). The engines that do which include the 4 cyl "Dynamic Force" engines, allow for a wide range of viscosities in non-USA markets, similar the the 1UR-FE V8 as seen above. And in his longer youtube video, there is no mention at all of this.
running 0-40W oil
