Do you really need any thicker than 0W-20?

[RamFan]

A manufacturer is not going to recommend an oil viscosity which will harm an engine. PERIOD. I'm looking to buy a CX-5 in the coming months and have done some research on the 2.5l i4, 0w20, 5w20, and 5w30 are all recommended, the only variance is location. 0w20 for U.S. and Canada. 5w20 and 5w30 for Mexico and others.

 

[Gokhan]

Originally Posted By: SlipperyPete
Doesn't the high VI and high NOACK of the OEM 0W-20's indicate an inferior base stock compared to the offerings from Shell or Mobil?

High viscosity index doesn't imply inferior base stock. In fact, it's more like the other way around.

Usually the biggest indicator of base-stock quality is the NOACK volatility. However, neither ExxonMobil nor Toyota discloses the specs of Toyota Genuine Motor Oils. Therefore, we don't know what the NOACK volatility is.

The biggest factor to the oil quality is the additive package, including the viscosity-index improvers. The base-stock quality comes a distant second but it can also make a big difference.

 

[Clevy]

Originally Posted By: Trav
Originally Posted By: Clevy
Originally Posted By: kschachn

Originally Posted By: aquariuscsm
20 wts are probably perfect for a 4-banger. Anything thicker would probably slow them down. A muscle car engine would probably destroy itself on a 20 wt.


Why is that exactly. If the engine has adequate oil pressure and volume what exactly is it missing causing a larger motor to destroy itself.

Crank flex its that simple. The more cylinders and less main bearings the more flex can occur.
For low viscosity oils to protect properly the crank must remain totally stable in its main bearing bores which use lower clearance bearings.

This is a serious consideration for anyone considering running lighter oils in older engines or engines not back spec'd for low viscosity oil.

http://www.enginebuildermag.com/Article/...and_racing.aspx


Good answer. K. Thank Trav. I'm going to read the link.
I wasn't being facetious when I asked. I am glad that you could give a sensible reason why.
But is this a real issue if only going one grade thinner? I know going thicker may affect fuel economy but is going one grade thinner a possible serious issue,and asking for catastrophe?
Thanks

Edit
Awesome link. Saved that to home screen.
Thanks Trav

 

[Trav]

Originally Posted By: kschachn
The crankshaft on my 4 cylinder cars is longer than the V6, and similar in length to the V8 on my BMW. I still don't see it.


Check the crank length on these engines. The V6 may only have 3 cyl on each side but they are staggered and your still going to have to make room for 6 rods.
Whats the distance between each main bearing? How many mains on the V6?

How many main bearings on the V8 BMW and how many on a Honda 4 cyl?

 

[Shannow]

Originally Posted By: RamFan
A manufacturer is not going to recommend an oil viscosity which will harm an engine. PERIOD.


no-one has ever said that a manufacturer is recommending an oil that will damage an engine...we've said maybe offer sub-optimal (to use their words, "still adequate") protection/longevity.

 

[gregoron]

To the original question, yes my car is spec'd for 5W-40, it burns oil, and I live in a warm climate. I'm not putting anything below 3.5Cp HTHS in my engine.

 

[CourierDriver]

This may help on oil thickness and so on: http://www.upmpg.com/tech_articles/motoroil_viscosity/ You can find the same stuff on the home page in here, but this is nice.

 

[Gokhan]

Originally Posted By: gregoron
To the original question, yes my car is spec'd for 5W-40, it burns oil, and I live in a warm climate. I'm not putting anything below 3.5Cp HTHS in my engine.

If it burns oil and you live in a warm climate, don't waste money on 5W-40. Use a quality 15W-40 like Mobil Delvac 1300 Super 15W-40. It will protect comparably to 5W-40 with similar OCI and the consumption will be definitely less than with 5W-40.

 

[KrisZ]

So, after one OCI and one UOA, which was not as steller as you make it out to be, you're proclaiming success?

Do you know what oil pressures you are running? Do you know oil temperatures?
I would not be so quick, if I were you, to jump to conclusions based only on very limited facts and lots of assumptions.

 

[Jim Allen]

Originally Posted By: Trav
Of course there is a need for oil with higher viscosity.
If the bearing clearances are larger like in many high HP or worn engines or the surface area of those bearings is too small you will wipe a bearing.
The oil pump type and pressure also plays a large roll in the equation.

From a technical standpoint the crankshaft must be either forged or hardened and be stiff enough to eliminate flex.
The more main bearings the better, thats the reason some 4 bangers with 5 mains are able to get away with running it without a forged crank.
The low clearance bearings would be quickly wiped out with a crank that flexed.
This alone knocks a lot of engines out from running light viscosity oil.

Anyone that says a low viscosity oil can be run in any engine is just running off at the mouth.
Knowing how the engine is constructed will determine if its a candidate for low viscosity oil not the amount of VI.


A sensible statement, which could be synopsized by "One size doesn't fit all, but one size many fit many."

 

[Clevy]

Originally Posted By: Gokhan
Originally Posted By: Rand
I'd stay conventional and change it frequently

Conventional/dino is either for people who don't know or for people whose engines burn oil.

With the prices of fully synthetic oil being so low nowadays, there is no reason to overlook their multitude of benefits in an engine that doesn't burn oil.

I went 5k miles and the oil was still very healthy. I don't intend to go more than 5k miles anyway.


Absurd comment. No matter how I cut the dice syn cost double over conventional. At 5000 mile intervals a conventional provides the same protection as syn,so at that mileage why spend double? That ridiculous.
I use conventionals as soon as the weather warms enough,and syns in our -40 winter. I like to change my oil and tinker with my vehicles but I don't like to waste money. I'm sensible and I don't need to spend double only to achieve the same mileage and think I'm doing my engine some kind of favour by running a syn.
Warm fuzzies sound expensive.
Your correct about the "people who don't know". A fool and his money are soon parted.

 

[CMMeadAM]

Originally Posted By: Trav
Originally Posted By: Clevy
Originally Posted By: kschachn

Originally Posted By: aquariuscsm
20 wts are probably perfect for a 4-banger. Anything thicker would probably slow them down. A muscle car engine would probably destroy itself on a 20 wt.


Why is that exactly. If the engine has adequate oil pressure and volume what exactly is it missing causing a larger motor to destroy itself.

Crank flex its that simple. The more cylinders and less main bearings the more flex can occur.
For low viscosity oils to protect properly the crank must remain totally stable in its main bearing bores which use lower clearance bearings.

This is a serious consideration for anyone considering running lighter oils in older engines or engines not back spec'd for low viscosity oil.

http://www.enginebuildermag.com/Article/...and_racing.aspx


Excellent article ! Thanks for the link. And yes, without a doubt, in MANY applications, you need MORE than a 20 grade oil !!!

 

[tig1]

Originally Posted By: Trav
So what are you saying here? Are you saying because you got away with using straight 20w in an old school engine everyone can use it without any problems?
It sure sounds like it or at least implying it.


I did use Valvo 20wt HD along with millions of others. However I switched to M1 5-20 in the 70s with no problems either except with the slight increase in oil consumption in my Dodge slant 6 old school American made engine.

 

[Clevy]

Crank flex its that simple. The more cylinders and less main bearings the more flex can occur.
For low viscosity oils to protect properly the crank must remain totally stable in its main bearing bores which use lower clearance bearings.

This is a serious consideration for anyone considering running lighter oils in older engines or engines not back spec'd for low viscosity oil.

http://www.enginebuildermag.com/Article/...and_racing.aspx [/quote]

Excellent article ! Thanks for the link. And yes, without a doubt, in MANY applications, you need MORE than a 20 grade oil !!![/quote]

I subscribed. Awesome link. I spent half the night last night reading various articles on that website.
Thanks again for the link Trav.

 

[KCJeep]

Originally Posted By: Gokhan

Is there really a gas-engine automotive application that really requires thick oil? Diesels, which generate a lot of abrasive soot particles, are a different story of course.


My old school design Jeep I-6 does. I had a recent UOA where my 5w30 had sheared well into 20 grade range, wear metals were two to three times what they should have been. I have seen this same pattern in other Jeep I-6 UOA's as well.

I will run the thick 30 or light 40 grades I prefer in this engine from here on out regardless of the time of year.

 

[Trav]

Originally Posted By: CMMeadAM
in MANY applications, you need MORE than a 20 grade oil

Exactly! I would love to run oil as thin as possible, it brings HP and fuel economy but i don't want to risk the engine if its not built for it.

Unfortunately there are some that say monitor your oil temp and pressure and tailor the oil to the engine that way. It doesn't work and is an armchair ball game, the reality is very different.

I see engines every day and have noticed a few things over the years. Blocks today have a lot of supporting ribs in the block to add rigidity, main bearings are wider and more are using 4 bolts or studs once the realm of high HP engines.
Crank materials are better and stronger than ever before, all this adds up to a very strong and rigid bottom end.

This type of construction is ideal for low viscosity oils, in fact running thicker oils may cause excessive heat from friction and have a bad effect on the bearings.
So what happens running lower viscosity oils in a less than ideal bottom end? Sure the pressure may be okay and the oil temp may be fine but what happens when driven hard?
The crank may flex and actually hit the bearings, this over time will wipe them out.

The problem is the the pressure temp thing is you will never see this occur on a gauge, once the crank regains its composure everything is back to normal.
Before attempting to run low viscosity oil in an older engine or one not spec'd for it you have to know a lot about the internal construction and know enough about it to make an informed decision.
Adding an oil pressure and temp gauge is not a bad thing its just not going to give you enough information under all conditions.

morning rant over.

 

[aquariuscsm]

I have a flawless UOA on a very hard run w/RP Synerlec 20W50. LOTS of short trips,lots of backroad racing,and lots of 90+ mph extended hwy runs. Ran smooth as silk on this oil. Wish they still made it and that I could still get it at $6 a quart

 

[Jim Allen]

Originally Posted By: Trav
Originally Posted By: CMMeadAM
in MANY applications, you need MORE than a 20 grade oil

Exactly! I would love to run oil as thin as possible, it brings HP and fuel economy but i don't want to risk the engine if its not built for it.

Unfortunately there are some that say monitor your oil temp and pressure and tailor the oil to the engine that way. It doesn't work and is an armchair ball game, the reality is very different.

I see engines every day and have noticed a few things over the years. Blocks today have a lot of supporting ribs in the block to add rigidity, main bearings are wider and more are using 4 bolts or studs once the realm of high HP engines.
Crank materials are better and stronger than ever before, all this adds up to a very strong and rigid bottom end.

This type of construction is ideal for low viscosity oils, in fact running thicker oils may cause excessive heat from friction and have a bad effect on the bearings.
So what happens running lower viscosity oils in a less than ideal bottom end? Sure the pressure may be okay and the oil temp may be fine but what happens when driven hard?
The crank may flex and actually hit the bearings, this over time will wipe them out.

The problem is the the pressure temp thing is you will never see this occur on a gauge, once the crank regains its composure everything is back to normal.
Before attempting to run low viscosity oil in an older engine or one not spec'd for it you have to know a lot about the internal construction and know enough about it to make an informed decision.
Adding an oil pressure and temp gauge is not a bad thing its just not going to give you enough information under all conditions.

morning rant over.




Again, well stated!

 

[Capa]

I'm a thin proponent but one size definitely doesn't fit all. As a generalization, manufacturers do allow some tolerances. Hence my Lexus GS 400 uses 5W-30 in the States but can use (I assume because of the colder climate) 5W-20 in Canada and possibly 5W-40 in Germany. I have run all three weights in my 14 year old vehicle.

 

[CATERHAM]

Originally Posted By: Trav
Originally Posted By: CMMeadAM
in MANY applications, you need MORE than a 20 grade oil

Exactly! I would love to run oil as thin as possible, it brings HP and fuel economy but i don't want to risk the engine if its not built for it.

Unfortunately there are some that say monitor your oil temp and pressure and tailor the oil to the engine that way. It doesn't work and is an armchair ball game, the reality is very different.

I see engines every day and have noticed a few things over the years. Blocks today have a lot of supporting ribs in the block to add rigidity, main bearings are wider and more are using 4 bolts or studs once the realm of high HP engines.
Crank materials are better and stronger than ever before, all this adds up to a very strong and rigid bottom end.

This type of construction is ideal for low viscosity oils, in fact running thicker oils may cause excessive heat from friction and have a bad effect on the bearings.
So what happens running lower viscosity oils in a less than ideal bottom end? Sure the pressure may be okay and the oil temp may be fine but what happens when driven hard?
The crank may flex and actually hit the bearings, this over time will wipe them out.

The problem is the the pressure temp thing is you will never see this occur on a gauge, once the crank regains its composure everything is back to normal.
Before attempting to run low viscosity oil in an older engine or one not spec'd for it you have to know a lot about the internal construction and know enough about it to make an informed decision.
Adding an oil pressure and temp gauge is not a bad thing its just not going to give you enough information under all conditions.

morning rant over.

Not true.
OT and OP gauge will tell you what your operational viscosity is for every second the engine in running. With experience you will know what minimum OP is required to maintain an adequate operating viscosity to avoid running an oil that is too light.

It's the reason I run 50+wt oil in older engines of mine and 20wt oils in more modern engines.