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#1783837 - 02/16/10 02:08 PM Re: truth-5W-20 better mileage thyan 5W-30? [Re: flinter]
Geonerd Offline


Registered: 08/05/08
Posts: 648
Loc: Aridzona
Originally Posted By: flinter
Thanks..
But will 5W-30 provide better protection than 5W-20 over the
life of the engine? Ive read some folks feel 5W-20 is too thin
and will never use it.


"Too thin?" It all depends on the bearing design.

All other things being equal (I know!), a 20W oil will generate a slightly thinner hydrodynamic 'wedge' of oil between bearing surfaces. If the bearings were already close to the limit, you may have problems. Since the potential gas savings are so tiny, many people feel that it's "better to safe than sorry" and chose to run the thicker oil. Doing so won't hurt anything - just look at those crazy Australians! They run Xw40 and even Xw50W in average Hondas, fords, etc. without any ill effects. There's a (US) guy on BITOG who runs M1 15W-50 in everything. His cars love it!
_________________________
92 Accord Wagon - The White Whale! 225K.
Oil du jour: Valvoline 10w-30 SM Dino, Pure One oil filter. 6K OCI. 35 MPG with sane hypermiling.

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#1783964 - 02/16/10 03:44 PM Re: truth-5W-20 better mileage thyan 5W-30? [Re: flinter]
Durango Offline


Registered: 02/15/07
Posts: 2007
Loc: Los Angeles, California
Originally Posted By: flinter
Hi,
Yesterday, my shop finally changed my oil in my 2005 Hyundai
Elantra with Motorcraft Syn Blend 5W-30. I believe all my
other oil changes they were using 5W-20, Quaker State dino.

Will I really see any decrease in my gas mileage with
the 5W-30?
Thanks



flinter,

The decrease would be so little you won't see it on the gas gage. I heard only that you'll see a significant increase by using 0W-20 oil but I can't see using it my truck/car unless the manuel say I can.

Durango

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#1783982 - 02/16/10 04:01 PM Re: truth-5W-20 better mileage thyan 5W-30? [Re: Durango]
simple_gifts Offline


Registered: 07/26/04
Posts: 8440
Loc: Middlesex County CT
Quote:

Ive read some folks feel 5W-20 is too thin
and will never use it.


If the mfg says to use it, it is not too thin.
_________________________
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#1784177 - 02/16/10 06:50 PM Re: truth-5W-20 better mileage thyan 5W-30? [Re: simple_gifts]
ScoobySTeveD Offline


Registered: 08/14/06
Posts: 30
Loc: Halton Hills, Ontario, Canada
I know of two Honda products designed for 5W20 that save 10% using Amsoil ASM 0W20 vs. Castrol Syntec 5W30. (Acura 3.2L V6, Civic 1.6L D-series.)

I know of one other high mileage 93 Civic designed for 5W30 with 350,000km on the engine saving 5% with ASM 0W20 vs. Castrol 5W30 High Mileage.
_________________________
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'04 Subaru STi Weekend Warrior
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'03 Acura TL Type S... wife's daily driver

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#1784207 - 02/16/10 07:23 PM Re: truth-5W-20 better mileage thyan 5W-30? [Re: flinter]
Gary Allan Offline


Registered: 09/28/02
Posts: 39806
Loc: Pottstown, PA
Originally Posted By: flinter
Thanks..
Ive read some folks feel 5W-20 is too thin
and will never use it.


Oil can be used as a mood modifier. It has been reported, as you have read, to have an affect on "feelings".
_________________________
http://lube-direct.com/gallan/

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#1784619 - 02/17/10 04:03 AM Re: truth-5W-20 better mileage thyan 5W-30? [Re: Gary Allan]
08_SHELBY Offline


Registered: 09/22/09
Posts: 157
Loc: Indiana
I read somewhere that using 5w20 is responsible for about 0.7% better fuel mileage than 5w30, on average.
_________________________
2008 Shelby GT500 Convertible 5.4 Supercharged
2005 Mustang GT 4.6L
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#1784638 - 02/17/10 05:29 AM Re: truth-5W-20 better mileage thyan 5W-30? [Re: 08_SHELBY]
Gary Allan Offline


Registered: 09/28/02
Posts: 39806
Loc: Pottstown, PA
Most driving events are 20 minutes or less. The use of a 20 weight reduces the parasitic losses during that time. The bigger the difference in visc, and the shorter the duration of the event, the more pronounced the difference in parasitic losses.

20 weights are closer to operating visc than 30 weights. It's about that simple.
_________________________
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#1784659 - 02/17/10 06:31 AM Re: truth-5W-20 better mileage thyan 5W-30? [Re: Gary Allan]
ScoobySTeveD Offline


Registered: 08/14/06
Posts: 30
Loc: Halton Hills, Ontario, Canada
Originally Posted By: Gary Allan
Most driving events are 20 minutes or less. The use of a 20 weight reduces the parasitic losses during that time. The bigger the difference in visc, and the shorter the duration of the event, the more pronounced the difference in parasitic losses.

20 weights are closer to operating visc than 30 weights. It's about that simple.


We're actually seeing the opposite right now... that it's the people who get the oil warm enough on longer drives to see the 20 / 30 properties that see the most difference. In winter in cold climates, your coolant may reach operating temperature in 3 to 5 minutes of gentle driving, but it will take two to ten minutes more (depending on driving style and speed) before your oil reaches temperature. If your oil is still below freezing, a 5W20 and 5W30 should be behaving relatively the same. It's once they get up to operating temperature that you see more viscosity difference.

That's our theory, anyway, to explain why our commuters see more benefit than the local guys by going to 0W20.
_________________________
Stephen D.

'04 Subaru STi Weekend Warrior
'97 Subaru Legacy L 2.2L Drivex Rally Car
'03 Acura TL Type S... wife's daily driver

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