The effects of 5W30 through small passages

[Danno]

Not when both manufacturing plants use the exact same process for machining and cleaning the blocks.
People who have visited both plants claim that is the case here.

Specifically who? Can you name names and link their testimony?
I have visited an engine plant myself and no way in heck could I verify manufacturing details in such detail, and the failures in QC before shipping the engines.
Plant was the International engine plant in Alabama. Start up production making the infamous Ford 6.0L diesel and the International 365 engine. Once we received the engine in the field we joked it was called the 365 because it broke down 365 days of the year.

 

[dlundblad]

On a cold winter Canadian (or any northern US state) morning, a 0W-20 will be thicker than a 5W-30 here in Miami. 5W-30 will work just fine where 0W-20 is recommended. And, conversely, the debris was not caused by the 0W-20 being too thin of an oil. Good video for looking at that engine up close.

Well said. This debunks the 0w20 small oil passages narrative.

 

[Boomer]

Watching all these engines (Toyota, GM, Ford, Ram, etc) fail and that have to be replaced or rebuilt, I wonder if this is more detrimental to the environment than opening up clearances, using higher weight oil and burning a tad more gasoline. Seems to me folks in charge of all of this have blinders on!

 

[SureshR]

It's not all the 20wt oils fault. Combine 20wt oil, plus 10,000mi oil changes, maybe add some fuel dilution or the oil gets too hot and the engine is toast.
Between 20wt and 10k oci I'd say pick one, you don't get both.

There are 20wt oils and 20wt oils. Some with HTHS around 2.6, and others that are a 2.9 so borderline a C2 oil. Big difference between the two - and that is just counting the laws of physics (oil shearing) rather than all the chemistry that goes into anti wear additives in the add pack, choice of base stock and so on.

 

[TacoFergie]

While I think modern TGDI engines are capable of some incredible performance and are a major advance in tech, I would never consider buying one that had only been in production a year or two. An engine that complex will take many years of warranty data and early life failures to allow them to refine and finish developing what the original product launch schedule did not allow.

The V35A has been out since 2018 where it was introduced in the LS500. It has had this same type of failure since it debuted. Toyota has known about this issue for nearly a decade now. The only reason it wasn't a hot ticket item is because LS500's are low volume and typical LS500 owners aren't car enthusiasts that follow or interact with facebook pages or forums when something happens.

 

[Sequoiasoon]

After all this I’ll switch to 5W30 or even 0W30. Going back to my OG AMSOIL Signature Series. I have two oil changes worth of 0W20 EP. Hopefully by then my Tundra will either have its engine replaced or their data says it won’t. So far no metal is present in the oil filter.

Tundra is spin on filter? Pick up a Filtermag from Summit Racing was cheapest. You could do 2, I only use 1 and always have. At least when you cut open you'll be able to see ferrous stuff. If plug options get a Votex to replace it.

If it looks like this you might have reasons to at least be concerned.

 

[ESP9935]

Highly unlikely that it's a design flaw in any sense other than they designed something they apparently cannot build in quantity to acceptable quality levels.

It's one thing to pass an engine test with jeweler's sample prototype parts that are in the middle of tolerance and far better than they have to be, it's quite another to pass that test with the worst part that still meets specs.



The elephant in the room here is a confluence of several key factors mostly related to or mandated by regulations:

• Bearings aren't allowed to have lead
• Clearances must be pushed as tiny as as possible to allow the usage of the thinnest oils for CAFE.
• CAFE requires a highly power dense engine with tremendous unit loading and complexity.
• Complexity creates many, many more lubricated surfaces with with slightly different speed/load profiles
  • The increasing use of engine oil as a hydraulic control fluid

Watching the teardowns of these Toyota 3.4L turbo engines, I just shake my head at incredibly complex they are. They make a Porsche engineer blush.

While I think modern TGDI engines are capable of some incredible performance and are a major advance in tech, I would never consider buying one that had only been in production a year or two. An engine that complex will take many years of warranty data and early life failures to allow them to refine and finish developing what the original product launch schedule did not allow.

The V35A doesn't have particularly tight clearances for an aluminum block:

Notably larger than the 3UR-FE:

 

[TacoFergie]

I have gone down this rabbit hole on another thread concerning the V35A. Here are my take-aways...

1. It's not a viscosity issue. There are threads on IH8MUD where there have been failures in other countries where they use Xw30, Xw40 and even Xw50.
2. It doesn't matter if it's produced in the US or Japan, if it's gonna go, then it'll go.
3. Hybrid models have the same engine and are failing as well. Unfortunately they get hosed and most are just getting short blocks that are hand assembled in a Toyota dealer shop by a technician that you hope is mildly versed in engine assembly. Also, Toyota's excuse for not including hybrids is that the hybrid motor allows for propulsion to get safely off the road in the event of failure. So far, every hybrid engine failure owner has said that once the engine died, so did the hybrid system.
4. Oil pressure specs are incredibly low on this engine. Idle spec is 4psi or higher, 2500rpm is 26psi or higher. That idle speed pressure seems wild. Also note that 26psi isn't necessarily bad, but adding 10-15psi of boost is a lot of additional load at 2500rpm might not be so great. Especially since the trend is to keep these engines as low in the rpm as possible as often as possible. So if your engine is already teetering on the low end of pressure specs, things can go south quick.
5. There has been no coloration between oil change history and failure rates. What I mean is that even people who are diligent or that did break-in oil changes like Lake Speed and then change oil at 5k or even 3k OCI's have still had failures.
6. Comparing simply the specs (see this post), the 3.5 ecoboost has TIGHTER main bearing clearances and recommends 5w30. But it's oil pressure specs are higher as well. Not that I'm saying 5w30 is the answer, but the V35A certainly doesn't qualify as have extremely tight tolerances.

My point is that the debris excuse is just that, an excuse for a problem that Toyota hasn't figured out how to fix economically. There is a major design flaw, bearing oil retention issue and/or an oil delivery issue, but we'll never truly know. Now with the recent updates to the recall they are pulling a fast one like GM and claiming they can use "Inspection Software" to evaluate if #1 Main Bearing has abnormal wear. How the heck does software tell you if you have a hardware problem? Only thing I can see is oil pressure monitoring and knock events. But deciphering that to pin point a bad bearing is a bit of a reach IMO.

The Toyota diehards still defend Toyota somehow. I would imagine their tone would change if it happened to them 400+ miles away from home towing their camper. Some of the stories I have read about when and where the failure happened as well as how everything was handled have been pretty horrible. Which is part of the reason I didn't get a new Tundra last year. Besides the engine issue, the overall quality of the 22+ Tundra has not been very impressive in the ones I test drove.

 

[goingplacesanddoingstuff]

0w20's only reason is fuel economy.

It does have significantly lower viscosity in extreme cold. That can be a benefit.

 

[KEVINK0000]

I’m thinking harmonics and block/crank flex.
Swarf is bogus.

 

[kschachn]

If the 20-grade oil molecule can make it through the third hole then so will a 30-grade. Or a 40-grade. Or a 50-grade.

Well said. This debunks the 0w20 small oil passages narrative.

Yeah that goofy narrative needs to die.

 

[kschachn]

It does have significantly lower viscosity in extreme cold. That can be a benefit.

Perhaps if your battery is marginal. Otherwise any oil is so thick in extreme cold that it's not going to make any difference.

The real issue is pumpability, and that is represented by the winter rating. If it pumps, it will flow and rapidly warm up.

 

[Prison_Mike]

After all this I’ll switch to 5W30 or even 0W30. Going back to my OG AMSOIL Signature Series. I have two oil changes worth of 0W20 EP. Hopefully by then my Tundra will either have its engine replaced or their data says it won’t. So far no metal is present in the oil filter.

Me too. I have one more jug of 0w20 Pennzoil Ultra Platinum that will go in either the Odyssey or Optima once they hit 5k miles, then I'm going exclusively to Mobil 1 ESP 0w30. I already had an engine replaced in the Optima. Not really looking to do it again while I still have the loan on it.

 

[Pablo]

What happened to the other thread already started with this video?

Post in thread 'Toyota Expands Tundra/Lexus Recall of 3.4TT'

Jun 14, 2026

Very interesting video from Dave’s Auto Center of tear down blown Toyota engine.




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• Dave Hess

• 

 

[SureshR]

If the 20-grade oil molecule can make it through the third hole then so will a 30-grade. Or a 40-grade. Or a 50-grade.

Yeah that goofy narrative needs to die.

In a different context, if there's a tighter hole the solution is more lube.

 

[ARB1977]

Tundra is spin on filter? Pick up a Filtermag from Summit Racing was cheapest. You could do 2, I only use 1 and always have. At least when you cut open you'll be able to see ferrous stuff. If plug options get a Votex to replace it.

If it looks like this you might have reasons to at least be concerned.
View attachment 343556

That’s not a bad idea.

 

[f355spider]

Specifically who? Can you name names and link their testimony?
I have visited an engine plant myself and no way in heck could I verify manufacturing details in such detail, and the failures in QC before shipping the engines.
Plant was the International engine plant in Alabama. Start up production making the infamous Ford 6.0L diesel and the International 365 engine. Once we received the engine in the field we joked it was called the 365 because it broke down 365 days of the year.

Wish I could remember where I saw them...I have read dozens of forums and media stories about this for the past few years. I believe the ones I saw (and referenced in forums) where both from media and also Toyota employees (who had been to both plants), thus seemed credible. As my first impression was the same as yours.

 

[thetricky]

It's not all the 20wt oils fault. Combine 20wt oil, plus 10,000mi oil changes, maybe add some fuel dilution or the oil gets too hot and the engine is toast.
Between 20wt and 10k oci I'd say pick one, you don't get both.

Ah but you can have the best of both worlds. Here is one example:

T

Post in thread '2013 Ford F-150 5.0L, 15k OCI, HPL PCMO 5w-20'

Aug 8, 2025

Viscosity seems to be getting slightly out of range. They flagged Chromium but outside of that this 15k interval matches close to the 7k sample. Is your Dad going to continue this interval and sample?

Yeah it’s used up. He’s going to keep a 14k mile interval.

• thetricky

And I do believe user direct rejection is going an eye watering 30k+ OCI on 0w-16 in his Toyota.

 

[ZeeOSix]

Getting back to the failing Toyota engines, per the clearance specs shown in post 47 and in the specs linked in post 49 it looks like the journal bearing clearance spec is running at the 0.0005 inch per 1 inch of journal diameter. Pretty much the same specs for the Coyote I posted in post 33. This is pretty much as tight as you'd ever want to build an engine too.

I haven't followed this Toyota engine fiasco much (I have a rock solid 2005 4.0L 1GR FE), but did watch the video in post 1 of the engine tear down and didn't see any real signs that any bearings failed from being over heated, which would mean a bearing was too tight or had lack of lubrication. Could be whatever caused them to start failing (the debris claim by Toyota perhaps) opened them up enough to where they didn't over heat as they continued to eat themselves up.

When you look at the clearance specs on newer engines they are tight, typically running at 0.0005 in per 1 in of journal diameter. And that's if parts were all made to the mid point of their specified dimensions. Like in post 33 for the Coyote, if the build tolerance stacked in the worse case, the journal bearing could be as tight as 0.00038 in per 1 inch of journal diameter.

Then there's the aspect of actually building parts to the drawings and specs. If manufacturing isn't done right, you could end up with bearings even tighter than the worse case parts tolerance stack-up. Everything is so tight that messing up one dimension on a part could start causing problems.

 

[edhackett]

Then there's the aspect of actually building parts to the drawings and specs. If manufacturing isn't done right, you could end up with bearings even tighter than the worse case parts tolerance stack-up. Everything is so tight that messing up one dimension on a part could start causing problems.

I found it interesting that the main bearing girdle has steel inserts. The top shell of the main bearing seats in the aluminum block. The bottom shell in steel. Aluminum has roughly twice the linear expansion coefficient of steel. It seems that would introduce an issue that would have to be engineered around, and maybe not a trivial one, given the close, critical clearances.

Is this a design that is being used successfully in other engines? This is the first I've seen of this. Engine design and anything other than very basic metallurgy are not in my wheelhouse.

Ed