Oil weight

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I found a great deal on a bunch of 50w oil. Question: I don't need that much weight in my oil. I want to drop the 50w down to a 30w. What can I add to the oil to thin it down to 30w? I need to know what to add and what the exact ratio would be..
Thanks
 
Originally Posted By: OVERKILL
Are you talking about a straight SAE 50?


I think he is.

Viscosity mixing calculations are always approximate, but doing some quick math:

1:1 0w20 / 50 will give you 25w35.

2:1 will give you 16.6w30.

That's just straight averaging there may be someone coming along shortly with a more science based approach....

But in South FL, I'd have absolutely no issue using a ratio of 1 quart of 50 and 2 quarts 0w20.
 
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Originally Posted By: Popsy
Add some SAE10 maybe.


Good idea there also....1:1 ratio.
 
Originally Posted By: Kuato
Originally Posted By: Popsy
Add some SAE10 maybe.


Good idea there also....1:1 ratio.

So if I added it one to on I would be at 30w? That doesn't seem right
. I would think maybe 20% of 10w to the 50w would give me my thirty. But besides going with an addition of another oil is there another additive I could use? How do major producing companies vary the weight of oil?
 
There's no in between viscosity, it's going to be either a 30,40, or 50 depending on how much and what you blend it. What is the exact oil you have? I can get a better estimate if I know.
 
Originally Posted By: gilbertsta
I think it's mercury, I have to ask it's in a big generic container


Probably Mercury 25w50, essentially about as thick as an SAE 50.

Assuming its right in the middle of the 50 grade range which is between 16.3 and 21.9 at about 19 cst @ 100C, its a very thick product.

http://www.widman.biz/English/Tables/J300.html

Plug the numbers in here

http://www.widman.biz/English/Calculators/Mixtures.html

Mixing a 19 cst oil with a 5w20 which are usually right around the 8 cst mark, you will end up at 12 cst @ 100 C which is a good higher end 30 grade. The cold properties will probably be similar to a 10w30, but we can't know for sure. It won't matter if you are above freezing. If you use any less than 1:1 ratio of 5w20 to 25w50 you will be in the 10w40 range, which still is fine for most cars calling for a 30 grade in Florida.
 
Originally Posted By: Kuato
Originally Posted By: Popsy
Add some SAE10 maybe.


Good idea there also....1:1 ratio.


You won't find any automotive oil in sae 10 and if you did it wouldn't be cheap.
 
When you mix weights of oils you do NOT get an oil that is the average of the mix.

It is much more complicated than a simple average of the numbers.

Also, when dealing with cold temperatures where the 50 weight would normally turn into wax the 50 weight will still turn into a wax at close to the same temperature even when mixed with a lower viscosity oil such as a 20 weight.
 
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In South Florida, you could just run the stuff straight and be happy.
A 25W-50, if that's what this stuff is, is still thinner at cold start in your area than was the 10W-30 I have in one vehicle or the 0W-20 I have in another at the right around goose egg temperatures we saw Friday morning.
This would not be my first choice or oil, but for around fifty cents a quart or so, it would be a deal.
 
Originally Posted By: Virtus_Probi
I would suggest that the oil you bought was not such a great deal if you really want a 30.


This. ^^^

Oil is cheap anyway, so why buy something that's the wrong weight for you application?
 
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Surprising to see so much discussion simply on viscosity and no one questioning the application, the additives of the oil, etc.
 
If it's QuickSilver oil, it's on the thick side. But Mercury has not sold any straight 50 in decades AFAIK ...

It's prolly 25W-50 ... I'd just dilute it with Supertech 5-20 1:1 and call it good. What are you going to run it in?

And no - you can't use solvents to thin it. 1.) the solvents will burn off and you will be worse off than you are now. 2.) Meantime they destroy film strength so your bearings take a beating ...

Use oil to thin oil - only !!
 
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