2024 Toyota Land Cruiser Oil Spec, Interesting...

[ZeeOSix]

I guess when I pulled my 5,000 pound trailer to Leadville, CO (elevation 10,000 feet) this pass summer with my 5.3 Silverado running 0w/20 it should have blew up.....especially at 90 degrees ambient temperatures.....

It's not about engines "blowing up" ... it's about engines wearing more if there's not adequate viscosity.

 

[CKN]

It's not about engines "blowing up" ... it's about engines wearing more if there's not adequate viscosity.

As much as I tow at elevation under harsh conditions you are going to have a hard time convincing me that 0w/20 isn't protecting the 5.3.
I am not getting in to yet another "thick vs. thin"-respectfully.
Not to mention the millions of accumulative miles on these motors-the vast majority running the speced 0W/20.

 

[ZeeOSix]

Something to consider—turbos are significantly cooled by the oil flowing through the bearing housing. A thinner oil has a higher flow rate and carries away more heat.

Turbos are fed oil volume by the PD oil pump. When the oil is hot, the flow rate is essentially going to be the same. The difference in specific heat of oil when hot is so small that it's not going to be seen. No turbo is going to suffer because it doesn't have a xW-20 at 210F flowing through it. More like it's going to suffer more than if a thicker hot viscosity was flowing through it.

 

[Glenda W.]

Especially in severe service. We had a run of commercial plow trucks come into the dealer with premature upper rod bearing wear(found after tear down). GM sent in the regional rep and the answer was going up a grade. Eventually GM released a HD fan clutch.

It's not about engines "blowing up" ... it's about engines wearing more if there's not adequate viscosity.

 

[ZeeOSix]

As much as I tow at elevation under harsh conditions you are going to have a hard time convincing me that 0w/20 isn't protecting the 5.3.
I am not getting in to yet another "thick vs. thin"-respectfully.
Not to mention the millions of accumulative miles on these motors-the vast majority running the speced 0W/20.

As pointed out many times ... a thicker oil is going to provide more wear protection than a thinner oil in use conditions like that. You really don't know if it's wearing faster or not because you haven't tore it down to look. But taking simple measures to help ensure it's better protected is as easy as going up a grade.

 

[edyvw]

Something to consider—turbos are significantly cooled by the oil flowing through the bearing housing. A thinner oil has a higher flow rate and carries away more heat.

That is if all things are equal. Oil composition also determines cooling capacity and heat exchange capacity.
If all things equal, benefit is negligible, and if it is a problem running 5W30 compared to 0W20 bcs. cooling, than the problem is in cooling system.
The advantage of higher HTHS on other hand in turbo engines is real.

 

[kschachn]

Turbos are fed oil volume by the PD oil pump. When the oil is hot, the flow rate is essentially going to be the same. The difference in specific heat of oil when hot is so small that it's not going to be seen. No turbo is going to suffer because it doesn't have a xW-20 at 210F flowing through it. More like it's going to suffer more than if a thicker hot viscosity was flowing through it.

Exactly. It’s not going to flow faster and the lower HT/HS is detrimental.

 

[ZeeOSix]

^^^ A thicker oil will only run a degree or two hotter under the same conditions. It that was an issue, no high performance car would come with anything thicker than xW-20, and high performance car makers (or even Toyota in their OMs) wouldn't be recommending thicker oil for harsh use conditions.

 

[edyvw]

^^^ A thicker oil will only run a degree or two hotter under the same conditions. It that was an issue, no high performance car would come with anything thicker than xW-20, and high performance car makers (or even Toyota in their OMs) wouldn't be recommending thicker oil for harsh use conditions.

That is also questionable. Motul 300V 5W40 runs actually bit cooler than Castrol Edge 0W30 I have in a sump now. Motul has HTHSof 4cP, Castrol 3.5’ish.
The composition of oil plays big role here too. But than, 2.1qt of Motul is some $40+.

 

[Hohn]

Turbos are fed oil volume by the PD oil pump. When the oil is hot, the flow rate is essentially going to be the same. The difference in specific heat of oil when hot is so small that it's not going to be seen. No turbo is going to suffer because it doesn't have a xW-20 at 210F flowing through it. More like it's going to suffer more than if a thicker hot viscosity was flowing through it.

Not quite. The PD oil pump is feeding the turbo in parallel with the other parasitic oil flows.

You seem to think that there’s a gerotor or gear pump feeding oil only to a turbo.

Not only that, but the oil pump has excess capacity in most engines at cruise rpm, so the nominal condition has the pressure regulator bypass cracked.

This is why many cars do not show any reduction in oil pressure with thinner or hotter oil; the higher flow through the bearings and such with the thinner oil is oil that would otherwise have been internal recirculated inside the oil pump operating in bypass.

But there is indeed higher oil flow occurring at the same oil pressure right up until the bypass is closed and the PD pump follows the output curve for the pump speed and oil viscosity.

But you are correct—going up to a 30wt will not harm a turbo. And I’m running 5w-30 in my own k20c4 which calls for 0w-20, so I’m agreeing with you in practice, not just in theory.

 

[ZeeOSix]

That is also questionable. Motul 300V 5W40 runs actually bit cooler than Castrol Edge 0W30 I have in a sump now. Motul has HTHSof 4cP, Castrol 3.5’ish.
The composition of oil plays big role here too. But than, 2.1qt of Motul is some $40+.

Yes, more than one factor involved. The bottom line is oil viscosity difference in steady-state operating temperature under the same use conditions isn't what people should be basing their viscosity choice on. The HTHS viscosity is really the best parameter, for those who understand the relationship between HTHS viscosity, MOFT between parts and how that correlated to engine wear.

 

[ZeeOSix]

Not quite. The PD oil pump is feeding the turbo in parallel with the other parasitic oil flows.

You seem to think that there’s a gerotor or gear pump feeding oil only to a turbo.

Obviously, the oil flow going to all parts of the oiling system is supplied by the PD pump - why would I think there's a separate PD pump for the turbo, lol ... only if it has a "pre-lube" or "turbo cooler" after shutdown pump on the circuit. The flow through each parallel path in the oiling system will be dependent on the oil pressure on the supply end of each parallel circuit path. So if you look at the pressure produced at the start of the flow path going to the turbo at a constant engine RPM and oil temperature, the flow going through that flow path and through the turbo will be dependent on the viscosity and local feed pressure. At a constant engine RPM, as the viscosity goes down, the supply pressure also goes down (even if the pump is still in partial relief), and therefore so does the pressure at the beginning of the flow path to the turbo. So you'd have to actually look at both factors going on in each separate flow circuit within the oiling system - that being the pressure and viscosity at the source of each independent parallel circuit.

Not only that, but the oil pump has excess capacity in most engines at cruise rpm, so the nominal condition has the pressure regulator bypass cracked.

Even so, the above would apply. The flow through each parallel circuit in the oiling system will be dependent on the pressure at the source of each independent parrallel circuit and the viscosity, regardless if the pump was in relief or not.

This is why many cars do not show any reduction in oil pressure with thinner or hotter oil; the higher flow through the bearings and such with the thinner oil is oil that would otherwise have been internal recirculated inside the oil pump operating in bypass.

Every engine I've had with a PD oil pump with a spring loaded pressure relief valve certainly does show higher oil pressure with a thicker oil, even at full operating temperature. It's really noticeable when the oil is colder and thicker of course. A simple spring loaded pressure relief valve can't perfectly control the max oil pressure. If it could, you wouldn't see a difference in cold oil pressure with different oil viscosity with the engine at the same RPM. Only a computer controlled pressure relief system with real time pressure sensor closed-loop feedback could do something like that.

But there is indeed higher oil flow occurring at the same oil pressure right up until the bypass is closed and the PD pump follows the output curve for the pump speed and oil viscosity.

In a fixed flow resistance path, like the parallel flow circuit to the turbo and back to the sump, the flow rate will be proportional to the supply pressure divided by the dynamic viscosity. So the flow with a different viscosity oil at the same engine RPM depends on how the supply pressure at the start of the turbo oiling circuit changes with the different oil viscosity, and yes how much the pump is in relief or not. If the supply pressure changes (gets lower) with thinner oil (lower viscosity), then then the pressure and viscosity factors could basically cancel each other out and the flow essentially be the same. In any case, using a slightly different oil viscosity isn't going to be noticeable to make any real difference if you could even mearure the difference in the first place.

But you are correct—going up to a 30wt will not harm a turbo. And I’m running 5w-30 in my own k20c4 which calls for 0w-20, so I’m agreeing with you in practice, not just in theory.

Good move ... going up a grade like that is going to do more good than not.

 

[Sedin26]

Do you wear a helmet when you drive? Because you never know when that engine is going to explode bcs. thicker oil.

Agreed!! Next time he’s at the dealer he should get a quote on a new long block, as it will be needed sooner rather than later!!!

 

[burbguy82]

Another variation of this variation of the thick vs. thin discussion variation.

Variously discussed in various ways in other various threads.

we all now know who @kschachn really is

 

[Shel_B]

Another variation of this variation of the thick vs. thin discussion variation.

Variously discussed in various ways in other various threads.

That's a variation of your past various comments. It seems you have a veritable vault of variations.

 

[ZeeOSix]

What would BITOG be without talking and debating about oil viscosity and all the other aspects of oil ... just a place where people are posting what they are doing, what they are watching on TV and what they eating 3 times a day? The "O" is for "Oil". Could change the name to BITOIOG ... "Bob Is The Oil Is Oil Guy"