Engine Oil.
Instructor
Joined: Dec 2005
Posts: 225
Likes: 3
From: Shelburne Vermont
Ok ... they call me the village oil idiot. I thought that a multi-viscosity oil meant that it had the combined flowing characteristics of the straight weight oils listed. So I thought that I would have the cold weather advantage of a 5W, and still have the track advantage of a 30W. So why not use a M1 0W-40W? Yes, I still hold the title above...
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Joined: Aug 2001
Posts: 5,364
Likes: 38
From: King George VA
Originally Posted by SERENITY_NOW
Ok ... they call me the village oil idiot. I thought that a multi-viscosity oil meant that it had the combined flowing characteristics of the straight weight oils listed. So I thought that I would have the cold weather advantage of a 5W, and still have the track advantage of a 30W. So why not use a M1 0W-40W? Yes, I still hold the title above...
The good news is that good synthetics are essentially multi-viscosity without VIs, so they don't need as much VI as a petroleum based oil does. For example, a 10w30 synthetic might not need any VIs. But, it is reasonable to say that the larger the spread, the more VIs an oil has, and a 0w40 probably has a lot.
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C66 Racing #66 NASA ST2, SCCA T2
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Last edited by C66 Racing; Jan 20, 2006 at 09:19 PM.
Le Mans Master
Joined: Aug 2000
Posts: 5,529
Likes: 1,943
From: Austin Texas
Originally Posted by Subdriver
The downside to mult-viscosity oils is that they need viscosity improvers, or VIs, to help them achieve those ratings. The VIs don't provide the protection of the basestock or the anti-wear additives. Plus, they can break down over time, so your 0w40 could turn into a 5w40, or 10w40...
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Joined: Aug 2001
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From: King George VA
Originally Posted by MitchAlsup
Actually the problem is that the 0W-40 break down into a 0W-30 or even a 0W-20. It is not the 'winter' number that get thicker, it is the operating number that reverts to the viscosity of the base oil.
Le Mans Master
Joined: Aug 2000
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From: Austin Texas
Originally Posted by Subdriver
Thanks Mitch. I edited my response based on what you wrote in the Oil Follies thread before I saw you had already posted here.
