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#4758618 - 05/16/18 10:01 AM Stp and oil viscosity
old1 Offline


Registered: 01/04/11
Posts: 981
Loc: Columbus Nebraska
Now I know many, probably most of you have no use for Stp oil treatment. But I still would like to know if I were to put one 15 oz bottle in 4 quarts of 10w30 conventional or semi synthetic oil, what would the equivalent viscosity of the mix be. Approximately, not precisely. Would it be like a 15w40, a 20w50, or something odd like a 15w 35????
_________________________
2014 Fusion 2.5 engine 5/20 QSUD
1965 Mustang 200 c/4 10w30 QS defy
1964 Ford Ranchero 302 c/4 15/40 Delo
1929 ford model A No filters, and 15/40 oil

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#4758636 - 05/16/18 10:19 AM Re: Stp and oil viscosity [Re: old1]
Vladiator Offline


Registered: 01/04/16
Posts: 724
Loc: NC
The viscosity would be 10w30, with a gob of STP floating in the pan. Many tests on YouTube show that STP does not dissolve/mix in oil, so it would have no way of affecting the viscosity.
_________________________
Thicker oils give protection for severe operations such as driving in mountains, pulling a boat, dusty conditions, short trips, high rpm, overloading, overheating and overcooling. Thin oils give MPG.

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#4758667 - 05/16/18 10:53 AM Re: Stp and oil viscosity [Re: old1]
MotoTribologist Offline


Registered: 02/03/16
Posts: 539
Loc: NJ, USA
It absolutely is miscible in oil.

15 oz. of that product to 4 quarts should still be an SAE 30 unless the starting viscosity of the 10W-30 was at the upper range of the spec. In that case it would be a low SAE 40.

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#4758685 - 05/16/18 11:11 AM Re: Stp and oil viscosity [Re: old1]
old1 Offline


Registered: 01/04/11
Posts: 981
Loc: Columbus Nebraska
So you are saying that adding approximately 12% of a product with as high of a viscosity as STp oil treatment will barely affect the viscosity of the original oil. What if I added one quart of 20w50 oil to the same 10w30??
_________________________
2014 Fusion 2.5 engine 5/20 QSUD
1965 Mustang 200 c/4 10w30 QS defy
1964 Ford Ranchero 302 c/4 15/40 Delo
1929 ford model A No filters, and 15/40 oil

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#4758686 - 05/16/18 11:14 AM Re: Stp and oil viscosity [Re: old1]
ctrcbob Offline


Registered: 01/01/06
Posts: 610
Loc: Mount Dora FL, Penfield NY, R...
I'm not as critical as others on the site. Years ago, when cars had Oil Pressure Gauges, my cars would sometimes show very low pressure. Especially at idle. One (blue) bottle of STP would fix that. If I would ever see my pressure lamp flicker, I'd have no problem adding any from the blue bottle. (The red bottle and the black bottle are different - I think one has more ZDDP and the other has more cleaning additives).

BTW; it mixes with your oil, no problems, and IT DOES NOT CLUMP.
_________________________
Bob CTRC USN Ret.
Mount Dora FL,
Penfield NY
Roswell NM

2018 Sonata 2.0T Limited
2015 Sonata Sport 2.0T Limited

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#4758688 - 05/16/18 11:14 AM Re: Stp and oil viscosity [Re: MotoTribologist]
oil_film_movies Offline


Registered: 06/13/16
Posts: 2423
Loc: MN
Originally Posted By: MotoTribologist
It absolutely is miscible in oil. 15 oz. of that product to 4 quarts should still be an SAE 30 unless the starting viscosity of the 10W-30 was at the upper range of the spec. In that case it would be a low SAE 40.
You're right. http://www.widman.biz/English/Calculators/Mixtures.html and put in 200 cSt for STP at KV100. I used a KV100=11 cSt for the 10w30, middle of the 30 range. 15 oz is about 11% there. I got 12.9 cSt for the mixture, which is barely thick enough to be a 40 weight. Therefore, I predict you'd get a lighter version of a 10w40 out of your experiment, almost a thick 10w30.

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#4758816 - 05/16/18 01:15 PM Re: Stp and oil viscosity [Re: old1]
compratio10_5 Offline


Registered: 12/07/15
Posts: 80
Loc: Pocatello, Idaho
This post caught my attention because I tested this exact thing in the Mechanical Engineering Lab at the University of Idaho when I was a student there 50 years ago. The oil pressure gauge that I installed on my 57 Ford read only a few PSI at hot idle so I added 1 quart of STP. The hot idle oil pressure then went up to 20 PSI so I felt much better, but then started wondering how it would perform in cold weather. The Lab had a Saybolt Universal Viscosity tester that timed the oil flow through a capillary tube at 210F and at 100F. The used 10W-30 oil with STP taken from my car tested in the 20W-50 viscosity range. I have always wondered how the HTHS (high temperature, high shear) viscosity and the cold cranking temperature would have responded but those more important measures of viscosity were not tested in those days.
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It's not what you don't know that hurts, it's what you think you know that ain't so. Will Rogers

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#4758899 - 05/16/18 03:14 PM Re: Stp and oil viscosity [Re: old1]
Johnny2Bad Offline


Registered: 05/20/13
Posts: 1721
Loc: Saskatchewan, Canada
STP is mostly an expensive bottle of Viscosity Improvers in a petroleum base; it increases oil viscosity. I'd hazard a guess at +20 SAE.
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'57 FL Straight 50 wt
'90 Miata 1.8L w/Rotrex Supercharger [Mobil1 0W-40]
'96 Ram 1500 [3.7L Mobil1 0W-20 / 1L 15W-50]
'01 PT Cruiser [Mobil1 0W-40]

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#4758932 - 05/16/18 03:55 PM Re: Stp and oil viscosity [Re: old1]
MotoTribologist Offline


Registered: 02/03/16
Posts: 539
Loc: NJ, USA
Or it would move it up to an SAE 40 or just a slightly higher SAE 30 as already shown in two previous posts.......

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#4758995 - 05/16/18 05:19 PM Re: Stp and oil viscosity [Re: old1]
BJD78 Offline


Registered: 08/05/17
Posts: 458
Loc: Nebraska
A consumer reports 1996 According to a 1996 test conducted by Consumer Report , adding STP made a 10w30 more like a 15w40 oil. Granted that was 22 years ago so maybe STP is different now, but that is what STP formulation did back then.
_________________________
2010 Forester:122K
2009 Sonata :189K
2010 Tucson:55K

OCI 5K using the cheapest dino oil I can buy,usually NAPA or TSC Travelers oil.

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#4759023 - 05/16/18 05:48 PM Re: Stp and oil viscosity [Re: old1]
old1 Offline


Registered: 01/04/11
Posts: 981
Loc: Columbus Nebraska
Thanks all!!
_________________________
2014 Fusion 2.5 engine 5/20 QSUD
1965 Mustang 200 c/4 10w30 QS defy
1964 Ford Ranchero 302 c/4 15/40 Delo
1929 ford model A No filters, and 15/40 oil

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#4759290 - 05/16/18 10:04 PM Re: Stp and oil viscosity [Re: old1]
addyguy Offline


Registered: 09/08/05
Posts: 14268
Loc: Canada
STP has stated that the 'goal' of their product is to raise the oil it is being added to by one viscosity grade.

Their example is it would turn a 10W-30 oil into a 15W-40 oil.

When I have seen UOA's where STP has been used, this is what I have seen - the oil is close to the next viscosity grade (some shearing occurs, so it is closer to the line between two grades.

I think in this day and age of severe fuel dilution in small, high-strung engines STP is just the thing to bring oil back to 'where its supposed to be'.
_________________________
2010 Kia Soul 2U - 2.0L I-4, auto; 124k miles.
M1 EP 10W-30; OEM Kia filter.

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#4759706 - 05/17/18 10:26 AM Re: Stp and oil viscosity [Re: addyguy]
oil_film_movies Offline


Registered: 06/13/16
Posts: 2423
Loc: MN
Originally Posted By: addyguy
I think in this day and age of severe fuel dilution in small, high-strung engines STP is just the thing to bring oil back to 'where its supposed to be'.
One possible problem with that: STP used Group I or II base oils, prone to oxidation in high-strung engines, and the VII chemicals in there have been said to be low-quality types as well. This could lead to extra piston deposits and varnish. Using just a little in a well-formulated full synthetic oil shouldn't be a problem since it'll mix with the oil's powerful anti-oxidant package and dispersants. .... I think.

Instead, amazon order some Schaeffers Moly E.P. Oil Treatment, at KV100=238 cSt, its thick and likely has better components. It contains antimony and organic components, with very little other unnecessary stuff. Thickener for sure.

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#4761410 - 05/18/18 08:47 PM Re: Stp and oil viscosity [Re: old1]
addyguy Offline


Registered: 09/08/05
Posts: 14268
Loc: Canada
...or STP's new 'Synthetic' Oil Treatment in the gold bottle.

Has lots of goodies the 'regular' blue-bottle doesn't - detergents and antioxidants.
_________________________
2010 Kia Soul 2U - 2.0L I-4, auto; 124k miles.
M1 EP 10W-30; OEM Kia filter.

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#4763826 - Yesterday at 11:10 AM Re: Stp and oil viscosity [Re: old1]
racin4ds Offline


Registered: 05/07/10
Posts: 878
Loc: Ocala, Florida
My 08 Subie with the 2.5 turbo motor likes the grey bottle (high mileage formula with extra ZDDP) I just put a bottle in this weekend on top of my Maxlife 5W30 and within a few miles noticed the engine was much quieter! The high mileage (150k) and the turbo really beat the oil up, a little more Viscosity IMO is a good thing.
_________________________
Just say NO to thin oils and M1!
05 F350 Powerstroke
05 Hyundai Tucson
08 Legacy GT
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