Is it true oil gets thin when hot? - Team Camaro Tech
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post #1 of 12 (permalink) Old Oct 22nd, 03, 11:00 AM Thread Starter
 
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Is it true that if you put Kendal 50w and it's in the high 90's and your engine is running 190-200 that it will not be 50w anymore, and turns more into 30w or even 40w? Or does it stay the same throughout the day?
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post #2 of 12 (permalink) Old Oct 22nd, 03, 11:23 AM
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A straight 50 weight will stay 50 warm or cold. A say 15w50 will be a 15 weight till it warms up then its 50. thats for the folks that live in places where it actually gets cold- helps the oil move faster on cold starts.

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post #3 of 12 (permalink) Old Oct 22nd, 03, 12:02 PM
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As mentioned, it should in theory stay the same, straight 50 should be 50, cold or hot.
However, after its been in the engine for awhile, thermal breakdown, oxidation, byproducts of combustion, blow by and many other items will contribute to a change of the oil more quickly. Thats where synthetics shine, they are more stable over longer periods of time by their design.
You get what you pay for in oils just like you do in the cars you buy.


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post #4 of 12 (permalink) Old Oct 22nd, 03, 12:51 PM
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Ditto what click said.

I have seen some oils come out like water after they were "over heated" "burned up" this is breakdown. So if it was 50wt and you tookit beyond what it can handle it will not keeo the same properties as it did when still cool, clean and not burned. Your oil pressure gauge will tell you when the oil is hot or too hot. I personally like to run an oil temp gauge as well.

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post #5 of 12 (permalink) Old Oct 23rd, 03, 06:40 AM
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ok, let me throw a monkey wrench in this....

If true 50 weight will always be 50 wt, but 15/50 wt designed for colder climates, being used in an area it was not designed for will cause it to break down easier right? (Especially after extended usage)

Question.... Then do oils designed for high milage cars, or vehicles that are for severe usage perform better with you common on the shelf oils, or specially designed oils like synthetics?

I guess what I'm trying to get at is I'd like some information on lubes that would help me out when choosing! I aint the fellow that sticks to one brand and one brand alone. Is there a NON VENDOR site that gives a brief description on oils weights and their usage?

I was wondering because for years a friend of mine had used 50 wt oil in ALL of his cars. From the Mustang the Camry, The Navigator, and the Escort. A mutual friend and mechanic told him he was insame to use that type oil, in the 4 cylinders and the 302's. I was under the impression that all 8 cylinders could use 50 wt oil without putting a strain on the oil pump assy. Is this a fact or fiction scenario?

Someone help a brotha out!!!!
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post #6 of 12 (permalink) Old Oct 23rd, 03, 07:32 AM
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A 15w50 isnt really designed for exteme cold climates, I just used that as an example. a extreme cold climate oil would be like a 0w20 or somewhere along there. There are no problems running a 10w30, 10w40, 15w50 in normal warm weather. Personally i would never run a straight 50 in a honda or toyota etc. They reccomend a 5w30 so thats what id put in. If the car has the stock engine, just use what they reccomend. If you have an older car where the clearances arent tight anymore, you could go a little thicker. You could lose performance (a few HP) going with a thicker oil. For synthetic oils i like Mobil 1. For normal oil I like Kedall GT-1.

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post #7 of 12 (permalink) Old Oct 23rd, 03, 07:34 AM
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Actually, for the sake of discussion, a 15W/50 has the viscosity of a 15 weight but provides the protection of a 50 weight under heat/load.

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post #8 of 12 (permalink) Old Oct 23rd, 03, 07:43 AM
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Thats a tougher question to respond to but I will take a stab at it.
The new 'higher mileage' petro oils are more than likely going to be more stable in their weight so as not to 'thin' out when it gets hot. The thinner oil is more likely to go past valve seals and weak gasket leaks. Thats just my guess since none of the petro companies really go to much into how it works, they just market it as 'high mileage oil'.
I would never recommend anyone running 50wt oil in a normal car engine. Sure the pump will pump it but as the engine goes thru warm up, dispersing condensation, putting up with blow by etc, that 50wt will break down sooner than a 10w-40 that moves or flexes with the temps. There are still alot of 'old school' guys around that think thicker is better just as they think a bigger bullet is better in hunting. Not so, its the placement that counts.
A drag racer might run 50wt but they dump their oil after each run most of the time so its not an issue.
Many draggers now are running synthetics and going a whole weekend on one change of oil if they dont tear into the engine, dislodging wear metals and contaminating the oil.
The modern syn's are a true engineering marvel. molecules are all standard size, they can beef up the additive packages to do what they want, but it all costs money. When it comes to a $3000 rebuild of a small block or a big high power motor for racing, does spending $50 for oil or $25 sound like better insurance that its running at its peak HP ?
I highly recommend annual oil analysis also, to help people know how their power plant is working, what might be wearing out and if the oil is holding up. Again, cheap insurance at another $25 to know that maybe a ring or bearing is starting to go, you can now cure the problem before it causes major damage.
Not sure that explains it completely but thats my 2cents worth from over 25 years of running syns and seeing them made. [img]graemlins/thumbsup.gif[/img]

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post #9 of 12 (permalink) Old Oct 23rd, 03, 09:27 AM
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I didn't know anyone in this day and age still ran straight 50wt. The only reason for doing that would be if the clearances were getting loose and you had low oil pressure. I don't even think any of the stores around here carry straight 50wt. As mentioned above use what is recommended by the manufacture (weight wise). When it comes to engine oil thicker is not better. Personally I like Mobil 1 and Amsoil if I am running synthetic and I like Valvoline if I am using petroleum based oil. Newer cars I run 10-30 and as the mileage gets up there (close to 100K) I switch to 10-40. Everyone has their theories and beliefs on what works for them. There is a lot of info on the web about oil, just do a search.

[ 10-24-2003, 01:43 PM: Message edited by: camaroman7d ]

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post #10 of 12 (permalink) Old Oct 24th, 03, 05:57 AM
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Team,

Thanks for all the input. Combines all of you answered my questions, and ended my curiosities. (Damn, never knew spelling that word would be so hard... lol)

As for my buddy, I'm not exactly sure what he was thinking with the 50 wt oils, but he sure doesn't put it in there anymore....

But what about smaller 8 cylinder engines. (in particular his 5.0) Can he used a 50 wt synthetic without causing damage? Or its better to put that wt oil in ONLY when you have a better quality oil pump? I was under the impression that any 8 cyl could handle it... but it looks like it's an oil pump issue as well as blow by, engine age, ect...

Jerry

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post #11 of 12 (permalink) Old Oct 24th, 03, 06:04 AM
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I wouldnt use a 50wt in any v8 engine unless the engine builder called for it due to design.
If its stock v8 in existing car, he should only use what the manufacturer recommends. No reason to use 50wt at all.
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post #12 of 12 (permalink) Old Oct 27th, 03, 10:43 AM
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"ALL" oil gets thinner as it gets hot...an oil rated as 10w30 would be the thickness of 10w oil (at a particuler temperature) when cold, and the thickness of 30w oil (once again at a "different" particular temp) when it gets hot... in other words, when it's cold, a 10w30 doesn't get as thick as a straight 10w would. All this is mostly useful getting a cold engine to crank over when it's freezing out.... once everything is warm, oil is pretty much oil, as long as you don't overcook it





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