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#3184195 - 11/10/13 07:44 PM Re: Whos using 15W40? [Re: Realtech214]
CourierDriver Offline


Registered: 12/27/09
Posts: 2964
Loc: Tennessee
Oil thinning and what is really going on: Its in the details on the Home Pages of BITOG----------------------------------------------------------------------------------------------------------
We left off discussing that a 0W-30 grade oil is not thinner than a 10W-30 oil. They both have the same thickness at operating temperature. The 0W-30 simply does not get as thick on cooling as the 10W-30. Both are still way to thick to lubricate an engine at startup.

I have heard several people say that Porsche specifically prohibits a 0W-XX engine oil, that it is too thin. Now here is the partial truth I spoke of earlier. We will discuss multi-grade oils. Earlier we said that a straight 30 grade oil has a thickness of 10 at the normal operating temperature of your engine. The multi-grade oils 0W-30 and 10W-30 also have a thickness of 10 at 212F.

The difference is at 75F, your startup temperature in the morning.

Oil Type Thickness at 75 F Thickness at 212 F
Straight 30 250----------------------------------10
10W-30 100 10
0W-30 40 10
Straight 10 30---------------------------------- 6
( Oil Type varying Thickness )

Now you can see that the difference between the desired thickness your engine requires ( = 10 ) is closest to the 0W-30 oil at startup. It is still too thick for normal operation. But it does not have far to go before it warms up and thins to the correct viscosity. Remember that most engine wear occurs at startup when the oil is too thick to lubricate properly. It cannot flow and therefore cannot lubricate. Most of the thick oil at startup actually goes through the bypass valve back to the engine oil sump and not into your engine oil ways. This is especially true when you really step on that gas pedal. You really need more lubrication and you actually get less.

Note that a straight 10 grade oil is also too thick for your engine at startup. It has a thickness of 30. Yet at operating temperatures it is too thin having a thickness of 6. It needs to be around 10. The oil companies have added viscosity index improvers or VII to oils to solve this dilemma. They take a mineral based oil and add VI improvers so that it does not thin as much when it gets hotter. Now instead of only having a thickness of 6 when hot it has a thickness of 10, just as we need.

The penalty is the startup thickness also goes up to 100. This is better than being up at 250 as a straight 30 grade oil though. Oil with a startup thickness of 100 that becomes the appropriate thickness of 10 when fully warmed up is called a 10W-30 grade motor oil. This is NOT as thick as a straight 30 grade oil at startup and it is NOT as thin as a straight 10 grade oil at full operating temperature.

The downside of a mineral based multi-grade oil is that this VII additive wears out over time and you end up with the original straight 10 grade oil. It will go back to being too thin when hot. It will have a thickness of 6 instead of 10. This may be why Porsche (according to some people) does not want a 0W-30 but rather a 10W-30. If the VII wears out the 0W-30 will ultimately be thinner, a straight 0 grade oil. When the VII is used up in the 10W-30 oil it too is thinner. It goes back to a straight 10 grade oil. They are both still too thick at startup, both of them. The straight 0 grade oil, a 5 grade oil and a 10 grade oil are all too thick at startup.

This is just theory however. With normal oil change intervals the VI improver will not wear out and so the problem does not really exist. In fact, oils do thin a little with use. This is partly from dilution with blow by gasoline and partly from VI improvers being used up. What is more interesting is that with further use motor oils actually thicken and this is much worse than the minimal thinning that may have occurred earlier.
Synthetic oils are a whole different story. There is no VI improver added so there is nothing to wear out. The actual oil molecules never wear out. You could almost use the same oil forever. The problem is that there are other additives and they do get used up. I suppose if there was a good way to keep oil clean you could just add a can of additives every 6 months and just change the filter, never changing the oil.



When the additives wear out in a synthetic oil it still has the same viscosity. It will not thin as a mineral oil. The fear that some say Porsche has that oils thin when the VII runs out is not applicable to these synthetic oils. These oils will always have the correct thickness when hot and will still be too thick at startup as with all oils of all types, regardless of the API / SAE viscosity rating.

Automotive engine manufacturers know these principals of motor oils. They know there is thinning or thickening that will occur. They take these things into account when they write that owners manual. Mineral oil change recommendations will generally include shorter time intervals than those of synthetic oils.

The reality is that motor oils do not need to be changed because they thin with use. It is the eventual thickening that limits the time you may keep oil in your engine. The limit is both time itself (with no motor use) and/or mileage use. The storage of motor oil in your garage, particularly mineral based oils, slowly ages the oil limiting its use later. Do not store huge volumes of oil in your garage that is exposed to extremes of temperature.

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Occurred: 05/13/13 01:57 PM


Edited by CourierDriver (11/10/13 07:46 PM)
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#3184347 - 11/10/13 10:44 PM Re: Whos using 15W40? [Re: CourierDriver]
Doug Hillary Offline


Registered: 05/30/03
Posts: 4816
Loc: Airlie Beach Australia
Hi,
CourierDriver - misinformation abounds. Your Reference said this:

"I have heard several people say that Porsche specifically prohibits a 0W-XX engine oil, that it is too thin."

Hog - or Pig wash......
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#3184425 - 11/11/13 02:02 AM Re: Whos using 15W40? [Re: Realtech214]
Sw296inchblue Offline


Registered: 10/04/09
Posts: 34
Loc: Colorado
I use it from Late April until late November. I love the robust add pack and the cheap price. A while back I picked up like 5 or 6 gal for $8.99 ea. Delvac. 7 months out of the year (in Colorado) I use it in: 1. Buick Rainer 112k. 2. Moms 03 Tahoe. 3. All my cycles.

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#3184750 - 11/11/13 01:04 PM Re: Whos using 15W40? [Re: Realtech214]
CourierDriver Offline


Registered: 12/27/09
Posts: 2964
Loc: Tennessee
The Bitog data i get from the home page is stuff I believe is written by someone with a lot more brain cells then I have got, that is why I post it. Now if some data has changed, the folks that run this site will know, but for now, the high tech stuff I read about oil is from the university data on the home page.

ok, thats my 2 cents worth...............
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#3184781 - 11/11/13 01:46 PM Re: Whos using 15W40? [Re: CourierDriver]
OVERKILL Offline


Registered: 04/28/08
Posts: 25659
Loc: Ontario, Canada
Originally Posted By: CourierDriver
The Bitog data i get from the home page is stuff I believe is written by someone with a lot more brain cells then I have got, that is why I post it. Now if some data has changed, the folks that run this site will know, but for now, the high tech stuff I read about oil is from the university data on the home page.

ok, thats my 2 cents worth...............


You don't need to reference the writing of Dr. Haas (who is a doctor, not a lubrication engineer, though he has certainly put a great deal of time and effort into his writings and they are excellent references even if not quite 100% accurate) when speaking as to the Porsche oil specs because Porsche has their own approval process and maintains a list of approved motor oils.

Here's a link that has the approval list from 2007:

http://forums.pelicanparts.com/porsche-9...-07-1701-a.html

You'll note there are MANY oils on that list that start with 0W-xx

Also, I think some of your oil theory may be a bit mixed up. Instead of re-hashing it here, please feel free to look at this thread:

http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1133544&page=5

Where I speak with respect to what you are attempting to convey in your earlier post.
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#3203059 - 12/01/13 03:39 PM Re: Whos using 15W40? [Re: Realtech214]
Richtrashman Offline


Registered: 10/21/13
Posts: 56
Loc: Cincinnati OH
Ran 15w40 in my chrysler 300m 3.5 one oc. Kinda dumb story i double gasket the oil filter and lost all the oil and all i had on the shelf was rotella. In it went! No issues whatsoever, it was december even. Prob 4qts rotella 1 quart mobil 5w30. My ford diesel mechanic buddy runs it in any engine not sohc or dohc says it wont hurt a thing in a pushrod engine. Now OHC is a different story.
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#3203315 - 12/01/13 08:33 PM Re: Whos using 15W40? [Re: Richtrashman]
artificialist Offline


Registered: 09/23/07
Posts: 6567
Loc: Florida
Originally Posted By: Richtrashman
Ran 15w40 in my chrysler 300m 3.5 one oc. Kinda dumb story i double gasket the oil filter and lost all the oil and all i had on the shelf was rotella. In it went! No issues whatsoever, it was december even. Prob 4qts rotella 1 quart mobil 5w30. My ford diesel mechanic buddy runs it in any engine not sohc or dohc says it wont hurt a thing in a pushrod engine. Now OHC is a different story.

I have heard some people say that the longer passage to the cam is a problem with 15w40, but I don't know if having an OHV engine eliminates the risk. Rocker arms, valve lash caps, and pushrod tips also need to be well oiled, and oil has to be pumped upward the same distance as it would in a SOHC or DOHC engine.

I have read conflicting stories on this subject when I frequented Saturn message boards. Some people would post a UOA that showed low wear with 15w40.
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#3203351 - 12/01/13 09:00 PM Re: Whos using 15W40? [Re: artificialist]
Richtrashman Offline


Registered: 10/21/13
Posts: 56
Loc: Cincinnati OH
In florida you could prob get away with it no prob, but in OH at 5*f it is awful thick when you crank the old SBC with 5 quarts of 15w40. You can hear the starter complain.
_________________________
2010 Optima 77k+ valv ML, ML ATF
1990 c2500 169k+ any oil
In the land of the blind the one eyed man is King


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#3212657 - 12/10/13 06:08 PM Re: Whos using 15W40? [Re: Realtech214]
sirgerman Offline


Registered: 10/18/09
Posts: 188
Loc: ca
until what winter temperature i can still use 15/40w diesel in my Saturn ?

thanks

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#3212712 - 12/10/13 06:59 PM Re: Whos using 15W40? [Re: Realtech214]
Clevy Offline


Registered: 11/11/10
Posts: 6995
Loc: Saskatoon canada
I use it in all my bike,including my Harley.
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#3212903 - 12/10/13 09:54 PM Re: Whos using 15W40? [Re: sirgerman]
Garak Offline


Registered: 12/05/09
Posts: 10993
Loc: Regina, Saskatchewan, Canada
Originally Posted By: sirgerman
until what winter temperature i can still use 15/40w diesel in my Saturn ?

In California? Until the sun burns out, I suppose. My Audi called for 15w-40 down to something like -15 C. Like anything, it's application dependent.
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Plain, simple Garak.

2008 Infiniti G37 coupe - Mobil Delvac 1 ESP 5w-40, Hastings LF113
1984 F-150 4.9L six - Quaker State GB 10w-30, Wix 51515

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#3213010 - 12/11/13 02:28 AM Re: Whos using 15W40? [Re: Realtech214]
Olas Offline


Registered: 12/11/13
Posts: 398
Loc: Manchester, England
I used 15w40 in my Scirocco for one OCI a couplle of years ago - it was about 3AM on Christmas Eve., and I split my sump on a speedbump about 100yards from my house.

Killed the engine, rolled into my parking space and left it till daylight.

Being Xmas eve, nowhere was open so I dropped the sump and cleaned it and welded up the split, threw it back on and filled up with the only oil I had to hand which was a Mineral 15w40. Fuel Economy was marginally reduced but it still cranked and fired up without any lifter noise or anything.

I just cant help but think that with my cam, spring pressure and shimmed, flat tappets, I need a decent film thickness and lots of zinc/moly/ws2 in there.. and I *FEEL* like 10w is the best comprimise of flowability and thickness.
Putting a micrometer on my cam lobes, and putting an internal vernier down my cylinder bores both back up my thinking wink


Edited by Olas (12/11/13 02:31 AM)
Edit Reason: posting before morning coffee...
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1457cc
98 bhp
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#3213078 - 12/11/13 06:15 AM Re: Whos using 15W40? [Re: Olas]
Garak Offline


Registered: 12/05/09
Posts: 10993
Loc: Regina, Saskatchewan, Canada
Originally Posted By: Olas
Putting a micrometer on my cam lobes, and putting an internal vernier down my cylinder bores both back up my thinking wink

How does that show a 10w-XX of any sort is actually optimal, and in comparison to what? I tell you right now that if you had a 10w-XX anything in a vehicle outside here right now, unless everything was in peak condition and you had a lot of luck on your side (and a working block heater), you would be leaving it sit there for the next week or until the tow truck showed up, whichever comes first.

This isn't a thick versus thin thing at all, but I rarely use a 10w-XX anything. The F-150 has it, but I don't need to do any measurements to determine there's no wear. It hasn't moved in ages.

If one wants a 40 grade, there are better options than 10w-40 in conventional or synthetic. There are better options than 10w-30, too. 10w-XX has jumped the shark, and that's beginning to be apparent in diesels, too, with 5w-30 and 0w-30 HDEOs.
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2008 Infiniti G37 coupe - Mobil Delvac 1 ESP 5w-40, Hastings LF113
1984 F-150 4.9L six - Quaker State GB 10w-30, Wix 51515

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#3213164 - 12/11/13 08:20 AM Re: Whos using 15W40? [Re: Realtech214]
Olas Offline


Registered: 12/11/13
Posts: 398
Loc: Manchester, England
Garak - measurements don't prove that anything is optimised but I feel like they show that my lube choice isn't causing any damage..
I thought that too thick an oil wouldn't get to the valvetrain quick enough and allow wear, and because I can't see or measure any wear the 10w must be sufficiently 'liquid' to get where it needs to be in a short enough time that no wear is taking place.

What is the outdoor temp. in Saskatchewan at the moment? Its around 8 or 9C where I am and the coldest winter I remember it got down to about -14 or -15C, 'Rocco still cranked and fired in those conditions and I don't remember it being any noisier than it usually is.. All anecdotal, but humans are funny like that wink
_________________________
1982 VW Scirocco
1457cc
98 bhp
1900 lbs
71000 miles
44mpg
Weber/Millers/Mahle/ITG/Leda/Michelin/Brembo/Pagid/Pioneer

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#3213184 - 12/11/13 08:43 AM Re: Whos using 15W40? [Re: Olas]
Garak Offline


Registered: 12/05/09
Posts: 10993
Loc: Regina, Saskatchewan, Canada
Originally Posted By: Olas
Garak - measurements don't prove that anything is optimised but I feel like they show that my lube choice isn't causing any damage..

Absolutely my point. 10w-XX may certainly be doing the job, but it's hard to try to claim science unless you do more than one engine and many, many viscosities.

Originally Posted By: Olas
What is the outdoor temp. in Saskatchewan at the moment?

Right now, it is a balmy -32 C. wink In any case, don't get me wrong. I'm not all fired up that a 0w-XX is necessary in this climate (or yours). Heck, me using a synthetic is an anomaly in the first place.
_________________________
Plain, simple Garak.

2008 Infiniti G37 coupe - Mobil Delvac 1 ESP 5w-40, Hastings LF113
1984 F-150 4.9L six - Quaker State GB 10w-30, Wix 51515

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