Oil viscosity fact question

[haley10]

These recommendations generaly apply to run of the mill "petroleum" oils. They are not considering synthetics.

The 5W-30 is preferred for it's cold cranking and cold flow abilities, because it starts with a somewhat thinner base oil and may have more pour point depressant additives.

Since the 5W-30 uses more viscosity index improvers to "prop it up", it is less shear stable.

The 10W-30 should be more shear stable and hold it's viscosity better under high temperatures and load.

The best of all world's would be to have a good 0W-30 synthetic.

Stressing the oil pump should not be an issue going to a 40wt. Many here like the 0W-30 German Castrol, where 30wt. is recommended. It's a thicker 30wt.

 

[crimsontide]

what about as far as a 20 weight....i have a ford....

 

[haley10]

quote:

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Originally posted by crimsontide:
what about as far as a 20 weight....i have a ford....

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Gotta remember this guy is in Europe and will be hittin' the Autobahn. He probably doesn't drive a Ford truck.

Can't get much more shear stable than a great 0-20 or 5-20. There is nothing to shear back to. The uoa's on Ford's with the Motorcraft oil sure are looking good.

The Conoco/Motorcraft seems to be some good stuff where a 20wt. is recommended.

 

[darkdan]

As far as the oil pump, they didn't change the oil pump when they stopped recommending 5w30 and started 5w20. =)

 

[Jeffrey Behr]

quote:

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Originally posted by crimsontide:
what about as far as a 20 weight....i have a ford....

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crimson, there've been dozens of notes on this forum to the effect that Ford's and others' recommendations of a hot-SAE20 oil are driven by federal fuel-economy calculations and requirements. I believe that a hot-20 will NOT protect an engine as well as a hot-30, which has MUCH higher HTHS (high-temp/high-shear) film strength.

Read this about Toyota's recommendations of MUCH-different viscosities for the same engine in the US v. Australia.

 

[Jeffrey Behr]

quote:

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Originally posted by SEC:
I have recently been reading about oil in various places and have the following question. If 0W30, 5W30 and 10W30 (for example) have the same viscosity when hot, why have I found more than one recommendation that 5W30 is most suited to ambient temperatures of about -20degC to 0degC, while 10W30 is for about -10degC upwards?
SEC

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Those initial numbers are the 'cold' viscosities. A thinner oil (indicated by the lower initial number) flows better in colder startup temperatures.

 

[haley10]

quote:

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Originally posted by Jeffrey Behr:

quote:

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Originally posted by crimsontide:
what about as far as a 20 weight....i have a ford....

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crimson, there've been dozens of notes on this forum to the effect that Ford's and others' recommendations of a hot-SAE20 oil are driven by federal fuel-economy calculations and requirements. I believe that a hot-20 will NOT protect an engine as well as a hot-30, which has MUCH higher HTHS (high-temp/high-shear) film strength.

Read this about Toyota's recommendations of MUCH-different viscosities for the same engine in the US v. Australia.

---

What about the good uoa's we are seeing??

 

[DavoNF]

SEC,

If you do a bit of driving on the autobahn's, I suggest a syn 0W-40. This should do you all year round, and stand up to a bit of high rev, high speed driving.

If the syn oil is too expensive, as it is here, try a 10-30 in winter and a 15-40 in summer.

Don't worry about the oil pump, they are a very robust design, although I don't know about a straight 50wt in sub zero temps.

Dave

[ March 06, 2004, 03:34 PM: Message edited by: DavoNF ]

 

[nicrfe1370]

Because he lives in the UK he therefore must drive the Autobahn? Do all north american residents go to Montana to drive fast? Jeffrey Behr is the only person to have answered his question.

 

[haley10]

quote:

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Originally posted by nicrfe1370:
Because he lives in the UK he therefore must drive the Autobahn? Do all north american residents go to Montana to drive fast? Jeffrey Behr is the only person to have answered his question.

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Well, I was sincere in trying.

He said he drove the autobahn. I've never been to the UK yet, but I figured it was pretty much like here. You can drive fast, but not for very long, because we have the State Troopers that will give you maximum misery in time and money for exceeding the speed limits. Hardly worth it.

 

[DavoNF]

quote:

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Originally posted by nicrfe1370:
Because he lives in the UK he therefore must drive the Autobahn?

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He said he did!

Having spent 4 years in the UK, as a professional driver, I have an intimate

knowledge of the roads and driving conditions there, and I gave my recommendations based on that knowledge.

Dave

[ March 06, 2004, 04:08 PM: Message edited by: DavoNF ]

 

[heyjay]

quote:

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Originally posted by SEC:
I have recently been reading about oil in various places and have the following question. If 0W30, 5W30 and 10W30 (for example) have the same viscosity when hot, why have I found more than one recommendation that 5W30 is most suited to ambient temperatures of about -20degC to 0degC, while 10W30 is for about -10degC upwards?

I have another question about going heavier than the recommended weight eg. using a 40-weight where a 30-weight is recommended? It seems to me this might strain the oil pump over time (I use my cars on German autobahns sometimes, with sustained high revs); is this correct, and would there be any other side effects?

Thanks for any information
SEC

---

Good question and welcome.

First, the standard ASTM D-445 Kinematic Viscosity test is run under low shearing forces at two standard temperatures: 40 C and 100 C.

It would be expected for all xW-30 oils to perform the same with this test, say a range of 11.5-12.5 cSt. The reference SAE 30 is 12.0.

There is a different test, the ASTM D-4683 HTHS (High Temperature High Shear) test which is run under high forces of one million shears per second and elevated temperature of 150 C.

You can expect readings such as 2.99-3.6 mPa s, which may make all the difference at WOT on the autobahn.

Since you're in the UK, why not check out the BP Lubricants web site? They're at:

http://www.bplubricants.co.uk

and they have a neat "recommendations" link.

As an example, a +2000 Honda Civic here in North America "requires" a 5W-20 oil.

According to BP, in Europe the same Honda 1.6 litre VTEC motor should use their premium synthetic 0W-40, and they have a wide range of viscosity for that motor:

"Engine oil viscosity recommendations: Below 35°C, 5W-30*; -20°C to 35°C, 10W-30; above -20°C, 10W-40; above -15°C, 15W-40/15W-50; above -10°C, 20W-40/20W-50. * Except cars fitted with H22A1, H22A2 engines which may only use 5W-30 below 0°C"

Remember that if you ask an oil viscosity question from North American site members, they usually must respond to what is "politically correct" for the North American market.

This is driven by EPA CAFE (Environmental "Protection" Agency Corporate Average Fuel Economy), which proposes hypotethical 0.6-1.7% "gains" applied fleet-wide to minimise or eliminate "gas guzzler" fines by running water-thin oils.

This helps somebody feel better about buying a Ford Excursion 6.8 litre V10 that gets 10 MPG.

The only way an oil can cause premature wear on an oil pump is if the oil is frozen. Where I live, it can dip to -42, and at that temp a regular 5W-30 or 5W-20 is frozen hard as a brick. You try to start the car and the oil pump drive will shear off.

So in my climate, I run Mobil 1 0W-30 to be safe in winter. In summer, I like to run heavier oil.

Hope this helps.

Jerry

 

[Jeffrey Behr]

quote:

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Originally posted by SEC:
...using a 40-weight where a 30-weight is recommended? It seems to me this might strain the oil pump over time (I use my cars on German autobahns sometimes, with sustained high revs); is this correct, and would there be any other side effects?
SEC

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SEC (Securities and Exchange Commission?)--
Hi-speed driving for an extended periods (even 10 minutes is 'extended' for most engines) strains and works the engine as no other use does and will heat (perhaps overheat) the oil VERY fast. That use benefits from the best high-temp/high-shear-rated (HT/HS) oil you can buy, and that'll be, among others even thicker, an nW-40 synthetic. The base ('cold') viscosity (it's NEVER 'weight'; the 'W' stands for 'Winter' or 'Winterized') would be determined by the coldest temp your car would experience during that oil-fill cycle. If it wouldn't get much below, say, -10dC, during that fill cycle, I'd use a 5W-40. If it would be much colder, I'd use a 0W-40, altho that raises other issues, such as the compromises inherent in the oil's needing lots of viscosity-index improver (VII) to get its range of viscosities that broad.

After much soul- (and BITOG-)searching, for my Porsche Cayenne Turbo, I've settled on Red Line 5W-40 in the nonsummer months* and RL 10W-40 in summer.


*I live in the Arizona desert in Phoenix. We never have winter, only fall and then spring, and then 6 months of summer. I see air temps over the pavement hit 130dF (54dC) about every day in June - August.

 

[Jeffrey Behr]

quote:

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Originally posted by nicrfe1370:
Jeffrey Behr is the only person to have answered his question.

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Thank you, nic; I do try.

SEC, I recommend you pay attention to info and advice from Jerry (hayjey); as nearly as I can tell, he's a very smart fellow.

I think I can summarize the advice here as follows:
1. Hi-speed driving is VERY tough on engines.
2. You need an oil with a high HT/HS rating.
3. Probably a synthetic nW-40 is your best choice.
4. Nothing bad will happen to your oilpump or any other parts of the engine; they'll just get better protection under high load and high heat with a high-HT/HS-rated oil.

And I too welcome you. You'll get lots of good advice form these folk; just read a lot and then make informed choices.

 

[Patman]

quote:

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Originally posted by heyjay:
So in my climate, I run Mobil 1 0W-30 to be safe in winter. In summer, I like to run heavier oil.

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I'm curious as to why you don't go with Mobil 1 0w-40 and simply run that all year round? Wouldn't it make things much simpler? The 0w-40 and 0w-30 M1 are both going to give you awesome cold cranking numbers, the edge going to the 0w-30 but not by a huge enough margin to neccessitate switching back and forth between the two, IMHO. I know M1 0w-40 has gotten a bad rap on here, and I've been known to jump in on that bandwagon too, but I do believe it won't thin out too much in a normally aspirated application, especially if it's not driven super hard.

 

[SEC]

I have recently been reading about oil in various places and have the following question. If 0W30, 5W30 and 10W30 (for example) have the same viscosity when hot, why have I found more than one recommendation that 5W30 is most suited to ambient temperatures of about -20degC to 0degC, while 10W30 is for about -10degC upwards?

I have another question about going heavier than the recommended weight eg. using a 40-weight where a 30-weight is recommended? It seems to me this might strain the oil pump over time (I use my cars on German autobahns sometimes, with sustained high revs); is this correct, and would there be any other side effects?

Thanks for any information
SEC

 

[TallPaul]

quote:

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Originally posted by Jeffrey Behr:

Hi-speed driving for an extended periods (even 10 minutes is 'extended' for most engines) strains and works the engine as no other use does and will heat (perhaps overheat) the oil VERY fast.

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I know what you mean. I am running a 10w40 rated at minimum 3.5 HT/HS. It gives me 45 psi hot at 2000 rpm. However, the other day we had some very high winds (maxing at 58 mph). It was around 60 F and I was on the expressway doing about 75+ and bucking the wind. After about 10 minutes of that, my oil pressure had dropped to 40 psi at 2000 rpm. After it cooled off when I was in the auto parts store, it was back to normal 45 psi hot at 2000. Can you guess what I bought at the auto parts store?
.
.
.
15w40 motor oil, which should give a better HT/HS.

 

[heyjay]

quote:

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Originally posted by Patman:

quote:

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Originally posted by heyjay:
So in my climate, I run Mobil 1 0W-30 to be safe in winter. In summer, I like to run heavier oil.

---

I'm curious as to why you don't go with Mobil 1 0w-40 and simply run that all year round? Wouldn't it make things much simpler? The 0w-40 and 0w-30 M1 are both going to give you awesome cold cranking numbers, the edge going to the 0w-30 but not by a huge enough margin to neccessitate switching back and forth between the two, IMHO. I know M1 0w-40 has gotten a bad rap on here, and I've been known to jump in on that bandwagon too, but I do believe it won't thin out too much in a normally aspirated application, especially if it's not driven super hard.

---

Pat:

I have thought of it, but M1 0W-40 is very hard to get around here. Since I end up changing the oil twice a year anyway, I don't mind the routine I now use.

I know that a lot of the local Chevy Silverado and GMC Sierra truck owners would kill to have my oil consumption results. Remember if your Vortec motor does use oil, GM now claims that 1 litre every 378 litres of fuel is "normal."

In April I'm still undecided on whether to go with Mobil 1 15W-50 or the new Mobil 1 Truck & SUV 5W-40. Both are the same price, and in summer of 2001 I had great results with the 15W-50 while towing a +8,000 lb trailer through Nevada and Utah.

The local parts place claims they will be carrying M1 T&S towards the end of March, so maybe I will try it.

Jerry

 

[SEC]

Thank you all for your answers. I am based in the UK. Before my next oil change in my Mazda Xedos 6, for which Mazda recommends only 5W30 and 10W30 (if anyone can tell me why, I would be grateful!) I will make a decision between:
- Mobil 1 0W40, available everywhere here but costly.
- Castrol 0W30, rarely available and even more expensive.
- Amsoil 10W30 synthetic, imported from the US by a company based in Wales.

I am leaning towards either Mobil or Amsoil, but know little about Amsoil other than what appears to me to be their rather aggressive marketing campaign on the 'Net.

I do drive autobahns when on holiday; I mentioned it due to the extended periods of near-WOT involved which most UK cars don't experience. Most of my other driving is on UK motorways. My OCI is typically 6-7K; I am reluctant to go to 3K intervals because this would be every few weeks for me.

I will find out where one gets UOAs done here.

Thanks again for your help.

SEC

 

[mikemc]

SEC, I am curious as to why Mobil1 10w30 is not on your list. Is it unavailable? I am a dino guy, but if I were to choose one synthetic for all year, M1 10w30 would be my choice.