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#1324571 - 12/29/08 08:29 AM Summer Fill: 5w30 or 10w30....which is better?
BigJohn Offline


Registered: 06/21/08
Posts: 768
Loc: Colorado
Assuming the same brand and type of oil, is 10W30 better than 5W30 for a summer fill?

When I look at the specs of PP for these two weights, it appears that 10W30 is superior in Flash Point, NOAK and HT/HS.

What else should be considered and what is important?

Thanks, John
_________________________
'14 Subaru Outback 2.5 CVT, M1EP 0w20
'10 Mercedes MLK350, M1 0w40
'01 Dodge Dakoka 4x4, 4.7 V8, MS5K 5w20
'04 KTM 950 ADV S, Royal Monarch 15w50

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#1324586 - 12/29/08 08:51 AM Re: Summer Fill: 5w30 or 10w30....which is better? [Re: BigJohn]
mcrn Online   content


Registered: 11/30/05
Posts: 2343
Loc: FL
I lean towards 10W30 in dino's not so sure about that when it comes to synthetics?

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#1324588 - 12/29/08 09:00 AM Re: Summer Fill: 5w30 or 10w30....which is better? [Re: mcrn]
Nyquist Offline


Registered: 10/24/08
Posts: 908
Loc: Iowa
It really depends on the application. Is it an older or newer vehicle?
_________________________
2011 Chevy Equinox 2.4L (Ecotec SIDI) QSUD 5w30 w/ ACDelco
2008 Chevy Cobalt 2.2L (Ecotec) Mobil 1 0w30 w/ ACDelco

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#1324591 - 12/29/08 09:03 AM Re: Summer Fill: 5w30 or 10w30....which is better? [Re: mcrn]
KW Offline


Registered: 09/04/03
Posts: 1685
Loc: Central Arkansas
I don't think it makes any difference which one you use in the summer. I like 5W30's over 10W30 now. But for years I ran 10W30 thinking 5W30 had more polymers in it. That don't seem to be the case anymore. And 5W30 is normally a heavier oil once up to temp.

So my answer is to use 5W30 year round but 10W30 will do just fine.

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#1324616 - 12/29/08 09:27 AM Re: Summer Fill: 5w30 or 10w30....which is better? [Re: BigJohn]
Pablo Offline


Registered: 10/28/02
Posts: 46555
Loc: Duvall WA - Pacific NW USA
 Originally Posted By: BigJohn
Assuming the same brand and type of oil, is 10W30 better than 5W30 for a summer fill?

When I look at the specs of PP for these two weights, it appears that 10W30 is superior in Flash Point, NOAK and HT/HS.



In theory you are correct but in reality not much if any practical difference. A 10W-30 should have less VII's.

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#1324620 - 12/29/08 09:35 AM Re: Summer Fill: 5w30 or 10w30....which is better? [Re: KW]
JHZR2 Offline



Registered: 12/14/02
Posts: 33283
Loc: New Jersey
10w30 historically was more shear stable, for dino and syn oils alike. The narrower spread was viewed as needing less/no VII which could break down and/or gunk up the works. Many older conventional 5w30 oils sheared down to 20 weight oils fairly readily.

The driver for 5w30 oils was supposedly faster flow and better cold start fuel economy... Remember, you may never see 0.1mpg in practice, but that over millions of cars adds to something.

Many were wary of 5w30 oils and using them unless really necessary. As they become more robust and shear stable, I would say why not?

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#1324703 - 12/29/08 10:58 AM Re: Summer Fill: 5w30 or 10w30....which is better? [Re: JHZR2]
SrDriver Offline


Registered: 12/09/06
Posts: 2404
Loc: Southeast Alabama
We live a few miles from the Florida line in southern Alabama and run 5W20 year around in both of our vehicles.

What does the owners manual recommend for your vehicle?

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#1325242 - 12/29/08 09:05 PM Re: Summer Fill: 5w30 or 10w30....which is better? [Re: SrDriver]
BigJohn Offline


Registered: 06/21/08
Posts: 768
Loc: Colorado
Owners manual recommends 5W30, but I have read that some of the newer 10W30 synthetics are awesome.

The difference in 5w or 10w when the temps never drop below 50 degrees in the summer....wouldn't seem that 10w would be an issue and if it is better in higher temps....then that would be a no-brainer to me.

Anyway, I am runing either 0w20 or 5w20 in the winter....just want to make sure my T4R is well lubed in the summer...especially when pulling 10-12k mountain passes and occasionally towing a 3k lb camper trailer.
_________________________
'14 Subaru Outback 2.5 CVT, M1EP 0w20
'10 Mercedes MLK350, M1 0w40
'01 Dodge Dakoka 4x4, 4.7 V8, MS5K 5w20
'04 KTM 950 ADV S, Royal Monarch 15w50

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