Question about oil grades

[LexusToyotanut]

Quick question about oil viscosity specifications in cars. Are engines/cars designed and based around a specific viscosity of oil, and SHOULD run that oil, OR are oil specs only in relation to the environment/tempature/ style of driving that the engineers expect the engine to be used in, so you may use whatever reasonable oil viscosity you feel is fit. Always been curious about this, thanks

 

[zray1]

Many cars, including my 2002 Jaguar XKR have factory viscosity recommendations on a sliding scale based on the ambient air temperature. For my car the range is from 0w-30 to 5w-40.

So for my particular climate I use the 0w-40, sometimes the 5w-40.

 

[userfriendly]

My guess... design the engine then test which oil it likes.

For fuel economy, VIIs can up the grade and increase the oil pressure without a corrisponding increase in HTHS.

 

[LexusToyotanut]

Many cars, including my 2002 Jaguar XKR have factory viscosity recommendations on a sliding scale based on the ambient air temperature. For my car the range is from 0w-30 to 5w-40.

So for my particular climate I use the 0w-40, sometimes the 5w-40.
View attachment 202294

Thanks nice answer

 

[redhat]

Two things come into play for US destined vehicles.

1. A viscosity that'll take the engine through the warranty period and not significantly impact the overall longevity
2. A viscosity that’ll allow their CAFE (corporate average fleet economy) numbers to be sufficient to reduce their amount of tax credits.

For example, say a 5.3 Silverado gets .4 MPG more on 0W-20 vs a 5W-30, that tiny increase can greatly help their fleets corporate average and equal out to less money GM is paying out to meet US EPA regulations.

That same 5.3 in the Middle East may call for 5W-30 or even higher. I’m paraphrasing here, but I recall my K24 Accord used to call for 5W-40 for the same engine in Australia.

I don’t think engineers explicitly design, an engine around a certain grade, more so designed for a range. Just as an engine builder will tell you what grade of oil to run based upon bearing clearances, the same thing applies.

You get into the whole debate of certain 30 weights that are as thick as a 40 weight, then some 40 weights that are just a thick 30… the lines get really blurred.

Unless super extreme climates, or a mechanical failure, an engine just about anywhere in the world should be able to regulate itself where its operating temperature does not fluctuate. Of course, you may have extremes, where an engine is overheating, or an extreme cold start. However, those are not normal running conditions. With that said the same operating viscosity or up to temp viscosity should be just fine.

 

[redhat]

And I’ll follow up by saying this. I doubt any manufacturer would grossly allow neglect on engine components with specing a certain oil grade.

Potentially would an engine have less wear on a higher viscosity… perhaps/maybe? But you’d have to do some analysis and check for yourself. For every instance of someone finding the golden ticket of the less wear on xW-40, you’ll prob find 10 that have shown little to no wear trend increases on 0W-20.

A lot of folks on here. Myself included do like er a little thick. But some of us also are reducing consumption too. So there’s auxiliary traits we’re trying to lick.

 

[oldhp]

I like how the car maker says "We recommend 0W20 BUT if it's not available 5W30 is suitable."

 

[shortyb]

Could be either/or. It's gotten way more complicated than the simple good ole days recommendations that were a sliding scale based on temperature/environment of use. That was when engine oil was much simpler too, and "oil was oil". Now there are several parameters that dictate what oil is recommended to be used, and many manufacturers have tried to simplify it again by assigning approvals (regardless of viscosity grade) or a viscosity grade with approval that is only one weight. Start with what is in the owners manual and go from there. You may find some leeway and expand from there. If you REALLY want to be confused, stick around and read the forums here .


I kid. There is lots of good information here at BITOG. You just have to sift through it all.

 

[dnewton3]

Quick question about oil viscosity specifications in cars. Are engines/cars designed and based around a specific viscosity of oil, and SHOULD run that oil, OR are oil specs only in relation to the environment/tempature/ style of driving that the engineers expect the engine to be used in, so you may use whatever reasonable oil viscosity you feel is fit. Always been curious about this, thanks

The topic revolves around many issues such as global location, warranty, environment, emissions, etc ...

Your question is adequately discussed (ad nauseum) in many, many, many threads on the site, including some you have already posted about.

Use the search tool, scan threads, read them and then make your own determination.

 

[goingplacesanddoingstuff]

Be prepared for some snarky comments inbound.

Generally you can change the winter number and be ok. Generally you can increase the second number and be fine too.

So, if your car specs 5w-30, is usually ok to run a 0w-30, 5w-40, or 0w-40. If your car specs 0w-20, it’s generally ok to run 0w-30 or 5w-30, etc.

But it’s up to you to determine if it’ll work in your car.

 

[PontiacHO]

Two things come into play for US destined vehicles.

1. A viscosity that'll take the engine through the warranty period and not significantly impact the overall longevity
2. A viscosity that’ll allow their CAFE (corporate average fleet economy) numbers to be sufficient to reduce their amount of tax credits.

For example, say a 5.3 Silverado gets .4 MPG more on 0W-20 vs a 5W-30, that tiny increase can greatly help their fleets corporate average and equal out to less money GM is paying out to meet US EPA regulations.

That same 5.3 in the Middle East may call for 5W-30 or even higher. I’m paraphrasing here, but I recall my K24 Accord used to call for 5W-40 for the same engine in Australia.

I don’t think engineers explicitly design, an engine around a certain grade, more so designed for a range. Just as an engine builder will tell you what grade of oil to run based upon bearing clearances, the same thing applies.

You get into the whole debate of certain 30 weights that are as thick as a 40 weight, then some 40 weights that are just a thick 30… the lines get really blurred.

Unless super extreme climates, or a mechanical failure, an engine just about anywhere in the world should be able to regulate itself where its operating temperature does not fluctuate. Of course, you may have extremes, where an engine is overheating, or an extreme cold start. However, those are not normal running conditions. With that said the same operating viscosity or up to temp viscosity should be just fine.

That same 5.3 in the Middle East may call for 5W-30 or even higher. I’m paraphrasing here, but I recall my K24 Accord used to call for 5W-40 for the same engine in Australia

Can you post this info from an owners manual for that 5.3 Silverado sold somewhere other than the US please?

 

[kschachn]

As noted, a topic that has been beat to death multiple times and in a variety of ways. Left, right, up, down and sideways. Also very related to your previous thread Castrol Australia website different from USA.

Of course all of this was already answered by multiple individuals in multiple ways, but here we go again:

No engine is "designed around" a specific grade of oil. It can be designed as to allow operation with certain thinner grades without incurring excessive wear, but this does not preclude the use of a higher grade. An engine is not damaged by an oil with a higher HT/HS but it can be damaged by an oil where the film thickness is too low.

What automakers do now (both here in the US and nearly worldwide) is to chase after increasingly stringent CO2 emission levels. CAFE here in the US used to be based on fuel economy but it changed to align with UK and EU regulations about CO2. Automakers have various strategies to accomplish this and one of the strategies is to utilize design changes that permit the use of thinner and thinner lubricants within the vehicle. This applies to the transmission and elsewhere not just engine oil.

It has less and less to do with operating environment (ambient temperature) than it did years ago. One can see this in the widespread use of oil coolers and other attachments, so the oil can be kept at a temperature which is low enough as maintain an acceptable MOFT that won't damage the engine. Correspondingly the recommendations for oil grade (which despite gross misunderstandings on this are still only recommendations) are now based entirely on regulatory requirements rather than engineering.

Automakers are spending boatloads of money to meet CO2 regulations. Engine oil is just one of the ways this money is being spent.

 

[Cujet]

Many modern car engines use connecting rods split at an angle (diesels have done this forever). This is to run larger rod bearings, and still be able to fit the rod down the bore, for assembly.

In the case of gas engines, the larger rod bearing is to allow the use of ultra thin oils without early failure.

The same goes for timing chains, the better manufacturers are now coating timing chain pins, to prevent rapid wear associated with ultra thin oils.

As always, the oil's film thickness is what keeps metal parts apart. A step up in viscosity is often useful in hot climates.

Also, some engines are well designed or simply work, and with regular service, will live a long life regardless of oil choice. Other engines, not so much. The Ford 5.4L 3V tends to fail early with the manufacturers recommendations. A simple switch to 10W-30/40 and 5K OCI's solves all.

 

[dnewton3]

Many modern engines use connecting rods split at an angle. This is to run larger rod bearings, and still be able to fit the rod down the bore, for assembly.

The larger rod bearing is to allow the use of ultra thin oils without early failure.

The same goes for timing chains, the better manufacturers are now coating timing chain pins, to prevent rapid wear associated with ultra thin oils.

As always, the oil's film thickness is what keeps metal parts apart.

I generally agree with the above.

Also, some engines are well designed or simply work, and will live a long life regardless of oil choice.

I agree with this also.

Other engines, not so much. The Ford 5.4L 3V tends to fail early with the manufacturers recommendations. A simple switch to 10W-40/5K OCI's solves all.

I would disagree here. Using a thicker lube isn't assured to "solve all". What it may do is delay or retard an issue. When this is done, along with other actions, it can mask the problem. It won't mitigate the issue; those actions make it dormant. I would say that it helps reduce the problem in many instances, but it does not "solve" the problem in all circumstances.

 

[Cujet]

(with regard to the 5.4L 3V Ford)

I would disagree here. Using a thicker lube isn't assured to "solve all". What it may do is delay or retard an issue. When this is done, along with other actions, it can mask the problem. It won't mitigate the issue; those actions make it dormant. I would say that it helps reduce the problem in many instances, but it does not "solve" the problem in all circumstances.

I brought up a specific example of the Ford 3V 5.4L engine. Some even consider it the worst modern engine. But the flaws are really related to the fact that the very conventional components cannot withstand ultra thin oils, especially with extended OCI's. The chains wear fast with low viscosity, and as the engine ages, the oil pressure is insufficient to make it to the cylinder heads, disaster results. The phasers also require more viscosity and will knock loudly, even when new, on 5W-20. People forget that these engines were "back spec'd" to thinner oil.

The local Ford dealer "fixed" the issue by servicing with 10W-40 and 5K OCI's. It should come as no surprise, it solved the warranty claims, and many fleet use/delivery 5.4L 3V engines lived into the 900K mile range with this program.

The 5.4 3V was not designed for ultra thin oils, and owners paid the price.

 

[LexusToyotanut]

I put Quaker state euro L 5w40 in the Lexus ls400 tonight. The oil filter is a pita, so I just drained the crank case. There’s less than half a quart of qsfs 5w30 in there. I’m sure they’re compatable

 

[Triple_Se7en]

I'm on-track this summer to do a 67%-33% blend using Castrol Euro 5w40 with Castrol Gold Edge 0w20.
Actually since I have nine five quart jugs that nobody wants for $10 each, I'll be doing a similar blend about eight more times.

In the meantime, if I find a low income, needy backyard mechanic that wants these jugs, I'll donate them for free.
So yes, your Quaker State frankenblend is compatible and so is the Castrol I'm about to use this Spring on my Hyundai.