Question about viscisity

[dennishiip]

I own a new Focus ST(2.0L turbo) and the recommended viscosity is 5W30. Having had German cars requiring 0W40 and/or 5W40 with European specs, I'm wondering why those oils would not be superior to 5W30 as per Ford. Seems to me that the 0W40/5W40 covers a greater temp range and has high specs. Does anyone understand the science or logic for 5W30 over 0W40/5W50 and why my car wouldn't be better off with the latter?

 

[Olas]

they spec thinner stuff for emmissions & economy. if you plan on getting it hot and using it hard a 40 would be better..

 

[Quattro Pete]

Originally Posted By: dennishiip
Seems to me that the 0W40/5W40 covers a greater temp range and has high specs.

It's a common misconception: thicker is not always better. Ideally, you should be using an oil that's as thin as possible and only as thick as necessary. And what is necessary varies by application. If Ford thinks that you don't need anything thicker than Xw-30, then they probably have a good reason for it.

Going with anything thicker than that will just rob you of fuel economy and power, but you will not necessarily benefit from the extra protection. Now, if you spend a lot of time at the track, there may be some benefit to thicker oil.

 

[dennishiip]

OK then,but doesn't the 0W and 5W winter rating mean it is not thick? I live in California and drive down central valley in 110 degree heat and was thinking the 40W would help in those conditions. I also wonder abut oils shearing down to lower viscosity after some miles rendering them less effective.

 

[Quattro Pete]

Quote:
OK then,but doesn't the 0W and 5W winter rating mean it is not thick?

0w- , 5w- describe how the oil behaves at very cold startup temperatures - something that's probably not very relevant where you live.

It's the second number in the SAE grade (-30, -40, -50) that helps determine viscosity at normal operating temp.

Quote:
I live in California and drive down central valley in 110 degree heat and was thinking the 40W would help in those conditions.


Does your ST have an oil pressure gauge? What pressure do you see when riding in that 110 degree weather? Is the pressure too low with Xw-30 oil? If not, I wouldn't worry about it.

 

[kschachn]

Why do you worry about that, have you seen it happen somehow? And if it does happen to some extent, how are they then less effective?

Originally Posted By: dennishiip
OK then,but doesn't the 0W and 5W winter rating mean it is not thick? I live in California and drive down central valley in 110 degree heat and was thinking the 40W would help in those conditions. I also wonder abut oils shearing down to lower viscosity after some miles rendering them less effective.

 

[Greasymechtech]

Oil temp and oil pressure gauge should help you decide.
UOA can also be used to see fuel dilution or shearing.

Where's the debate fall when you lose control of oil temp or pressure?

Do you trust your manufacturers with their history of recalls, bulletins, and other known issues?

Will you modify it with intake, exhaust, tuning, or..... ??

I don't see the thicker grade as better. I see it as a bandaid for mods or OE issues.

 

[Ken2]

Originally Posted By: dennishiip
OK then,but doesn't the 0W and 5W winter rating mean it is not thick? I live in California and drive down central valley in 110 degree heat and was thinking the 40W would help in those conditions. I also wonder abut oils shearing down to lower viscosity after some miles rendering them less effective.
What you say is all true, but not necessarily a problem. Often a 0W or 5W will have a lower intermediate viscosity, say at 40°C, than a 10W oil of the same hot viscosity, say a 30.

There are two types of shearing, temporary and permanent. The oils contain polymer bits called viscosity index improvers that change shape as the temperature changes. These bits can be stretched when under stress, and that is temporary shearing. The bits can be broken under greater stress, and that is permanent shearing. Better oils use higher quality VIIs that better resist shearing.

What warranty does your car maker put on the engine? And what extended warranty do they offer for you to buy? These are examples of the car maker putting their money on the line saying that their recommended oil does the job.

So, in the summer if you want to use a 5W-40 synthetic oil designed for European gasoline engined cars, do it. You'll feel better, and it can't hurt your engine. There might be a gas mileage hit so small that you probably don't see it.

 

[yvon_la]

Oil thickness has little say,the oil is chosen for lowest possible yearly maintenance cost.(if you can't make a car as reliable as say a Honda or you aren't sure?you ll aim for lowest yearly maintenance cost that can be evaluated!ya so car maker went stupid on that front with Japan car maker laughing and yelling NOOBS

 

[Rand]

the only worry I would have is about the oil shearing out of grade or fuel dilution pushing it out of grade with a Turbo-direct injection motor.

I would use a stout 5w30

for example NOT M1 AFE 0w30

many of the long life euro spec 5w30 would be more than adequate

or you could use m1 0w40, or mix in a couple quarts 0w40 with m1 5w30
if it makes you feel better.

Just driving it in 110F isnt bad, flogging it up a mountain, or tracking it could possibly warrant a thicker oil.. really just to make sure it isnt out of grade too thin near the end of the OCI.

 

[TiredTrucker]

Some perspective. Current 15L diesel engines from Detroit are being factory filled with 10w30. The Lubrication manual on these is quite comfortable with 30w oils on up thru severe heavy haul. The normal haul trucks are grossing 80,000 lb, running anything from Yuma and Death Valley, to Vail Pass and a thousand other passes, and on up well into Canada. Several fleets with millions in equipment have switched their shop bulk oil over to 30w. If 30w can handle that stuff, it is more adequate than a lot of people seem to think. If Ford seems to think that it is fine for their 2L turbo, not sure why anyone would feel the need to doubt it.

 

[CATERHAM]

Originally Posted By: dennishiip
OK then,but doesn't the 0W and 5W winter rating mean it is not thick? I live in California and drive down central valley in 110 degree heat and was thinking the 40W would help in those conditions. I also wonder abut oils shearing down to lower viscosity after some miles rendering them less effective.

No the 0W and 5W winter rating has absolutely nothing to do with how thick the oil is once up to operating temp's, it's the second number of an SAE multi-grade oil that determines that.

When a manufacturer spec's an oil grade there is no advantage of using anything heavier because they have already factored in everything that can happen to reduce the operational viscosity of the oil, including oil shear, fuel dilution and high oil temp's. For example Ford spec's 5w-20 for their 400+ HP Mustang GT and even for track use on the hottest days possible Ford specifically does not recommend using a heavier grade oil, doing so would actually be counter-productive.

BTW, regarding German cars, running 40 and 50 grade oils may be common practice in Europe for a number of reasons, but that doesn't mean it's automatically required and the 30 grade is spec'd for most makes such as Mercedes, Audi, VW and BMW. And regarding BMW, 0W-20 is even spec'd for their new cyl turbo, see below:
http://www.generaloils.net/2014-02-12_AIS-InfoFuchs_TITAN-GT1-EVO-0W-20_EN.PDF

Without trying to figure out how heavy an oil you need to use for yourself based on oil pressure and oil temp's, running the lightest oil grade recommended by the OEM will provide you with all the high temperature extreme use protection you'll need and them some.

 

[kschachn]

What is the spec that Ford requires for this engine that M1 AFE does not meet?

Originally Posted By: Rand
I would use a stout 5w30

for example NOT M1 AFE 0w30

 

[jrustles]

Always remember these BITOG rules:
-pressure = lubrication
-thinnest oil that will register oil pressure is all you need (0w20 for now, 0w8 for future)
-OW is more critical when you live in a hot climate, saves fuel, stops start up wear
-Kinematic Viscosity measured against the force of gravity is the only viscometric you need to know
-'thicker is better for protection is wrong' and you should feel ashamed for falling for it and living in the 70s and being an overall luddite
-turbos and engines are really good these days, what with their new fangled oil lubrication and water cooling, they don't even need oil lubrication anymore its just there to appease the luddites
-some North American owner's manual editing company employee (non-engineer, unidentified) knows best, always has, always will.

Stick to these points, and you'll do fine here kid!

 

[Rand]

Originally Posted By: kschachn
What is the spec that Ford requires for this engine that M1 AFE does not meet?

Originally Posted By: Rand
I would use a stout 5w30

for example NOT M1 AFE 0w30


its a 30wt oil that often goes out of grade thin and was designed for fuel economy.

Also my comment wasnt made in a vacuum it makes more sense when taken in context of my whole post.

for example if I quoted you saying

Originally Posted By: kschachn
What is the spec that Ford requires for this engine


It would mean something different than your whole sentance.

 

[ARCOgraphite]

Pressure HELPS lubrication but is NOT the only consideration for choosing the appropriate viscosity. The BITOG heavy hitters are a bit off base here. There are many splash and fog lubed parts that might require a higher viscosity under certain extreme loading conditions - and I personally think these conditions are becoming more prevalent with the more widespread application of CVT trans that hold the engine at PEAK HP - ~5500 rpm - for many seconds on a highway merge and talso the more common installation of smaller displacent supercharged engines in 2 ton vehicles.
For yet again increased safety margin you could have the higher DP doping rates allowed in the ACEA A3B4/API-SL specification oils that may help hard-run engines.

 

[Greasymechtech]

Isn't Ford the automaker that started the 5w20 bandwagon??? 5w50 for a certain performance car and now 5w30 for a turbo-4. What's that tell you? 5w20 not good enough?

Find UOAs on this engine regardless of vehicle to see what is happening. Or, UOA yours.

When no one is looking, use a quart of 0w40 or 5w40, and top off with any fullsynth sn/gf5/dexos 5w30 or boutique oil equivalent for your oil change intervals.

When more data on that engine is collected, you can choose more appropriately.

http://www.widman.biz/English/Tables/J300.html

0w30afe tends to shear quickly into a 20 grade. Might not good be the best choice if visc is needed.

 

[kschachn]

So one should not believe ExxonMobil when they say:

"Mobil 1 0W-30 Advanced Fuel Economy is engineered to offer the same high temperature/high shear viscosity performance as 5W-30 and 10W-30, so it is a good fit for the Florida heat. You can use it with confidence. Same goes for Mobil 1 0W-20 Advanced Fuel Economy and 5W-20."

 

[kschachn]

Where is everyone seeing this?

Originally Posted By: Greasymechtech
0w30afe tends to shear quickly into a 20 grade. Might not good be the best choice if visc is needed.

 

[CATERHAM]

Originally Posted By: ARCOgraphite
Pressure HELPS lubrication but is NOT the only consideration for choosing the appropriate viscosity.

First remember that the statement "pressure equals lubrication" is the basis of a disingenuous strawman argument that no one that understands the subject has ever made.
Despite what some thick oil advocates would have you believe, when one refers to oil pressure what we are really referring to is operational viscosity. And since an OP gauge is a viscosity meter, referring to OP is therefore a proxy for operational viscosity.
Pretty simple really but there are some that love to confuse rather than enlighten.