Food For Thought re. "Thick" vs. "Thin"

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This from the "Tech Correspondence" section of the May, '06 issue of Road & Track: "OIL WEIGHT QUANDARY I've been using Redline oil in my 2002 Sabaru Imprezza WRX since its original break-in period. The air temperature where I live rarely dips below freezing. I understand 5W-30 is recommended but chose 10W-30 due to its tighter viscosity range, which should mean fewer additives and less chance of lubricant breakdown under extreme conditions. The car has 60,000 trouble-free miles including eight or ten track days. Would the lighter weight oil be better for the engine? I suspect this is probably overkill, but both oils are offered, so there must be a difference. Ken Levin Point Reyes Station, California We'd stick with the slightly heavier weight 10W-30 for just the reasons you cited. Plus, if you are track driving, the narrower viscosity range should perform better with the elevated oil temperature you're sure to get at the track, and cold-start lubrication should not suffer because you aren't subject to truly cold starts. The very thin 0W and 5W oils are relatively modern lubes aimed mainly at improving fuel economy by reducing internal engine drag." Flail away! (If anyone is really at odds with the response, express your reservations to: [email protected], or Technical Correspondence Road & Track 1499 Monrovia Ave. Newport Beach, CA 92663 Don't forget to include your first and last name, hometown, and state. I'm certain all correspondence will receive appropriate consideration. [Wink] )
 
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In theory, 5w30 and 10w30 should act the same at operating temps. The benefit of 5w is better flow when cold, thus reducing wear and gas consumption when cold. If one is either track driving, or doing lots of highway driving, i think going with a 10w30 makes a lot of sense. If one is doing lots of short trips and lots of cold starts, i think going with a 5w30 makes sense. If one is doing lots of cold starts AND driving very hard and long between oil changes, perhaps a semi or full syntheitc 5w30 is in order. I just dont think the "thick vs thin" debate can ever be answered. Too many factors and too many different applications. Each situation needs to be looked at independantly, and the right oil chosen for THAT situation. I like to use 5w30 in the winter and 10w30 in the summer. My owners manual allows for either to be used across a wide range of temps. To be honest, i find very little difference between the two. In reading the spec sheets for various oils, in order for the oil companies to make their 10w30's meet the EC spec, their 10w30's look a LOT like 5w30's on paper anyway. If you get into the high mileage (and thus usually not EC) oils, then the difference is greater.
 

Ray H

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Perhaps someone's personal motor oil database would benefit from re-reading the temperature recommendations for the 5W oils, <i>circa</i> 1958. Those now 48 year-old 5Ws with their early generation VII polymers were intended as a winter grade motor oil to aid cold starting in sub-zero weather. There were specific cautionaries about <i>not</i> using those viscosities at all for general use in hot climates and/or high load applications.
 

JAG

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Forget 1958 and focus on today (directed at G-Man, not Ray). If you can get away with not using viscosity index improvers for an oil used in racing, do so.
 

JAG

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Good point. In the case of Redline, the 5W-30 and 10W-30 are so similar (HTHS, volatility, viscosities, etc) that both seem equal for racing use.
 
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quote:
Originally posted by Ray H: Perhaps someone's personal motor oil database would benefit from re-reading the temperature recommendations for the 5W oils, circa 1958. Those now 48 year-old 5Ws with their early generation VII polymers were intended as a winter grade motor oil to aid cold starting in sub-zero weather. There were specific cautionaries about not using those viscosities at all for general use in hot climates and/or high load applications.
For Ray and JAG: My post was directed at the guy's unqualified statement that 0w and 5w oils are "modern" inventions. That's just not the case. Please see my post in the 58 Imperial thread where I state the following:
quote:
I think 5w20 was a seasonal oil that was only sold during the winter months in the extreme north and in Canada. Given base oil technology at the time, winter driving where the daytime high temps rarely got above freezing would be the only "safe" conditions to use 5w20 back then.
 

JAG

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That's cool G-Man. I wasn't trying to give you a hard time or doubt what you said. I was just trying to keep us focused on the basics of his message which has a good basis even though some of the finer details were no good.
 
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quote:
Originally posted by Ray H: I've been using Redline oil in my 2002 Sabaru Imprezza WRX since its original break-in period. We'd stick with the slightly heavier weight 10W-30 for just the reasons you cited. [email protected], or Technical Correspondence Road & Track 1499 Monrovia Ave. Newport Beach, CA 92663
Looks like Mr. Technical Correspondence doesn't know much about RedLine oils. Although it's a reasonable answer for cheap dinos in this application.
 
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quote:
The very thin 0W and 5W oils are relatively modern lubes aimed mainly at improving fuel economy by reducing internal engine drag.
Relatively modern? I think someone needs to show him that page from the 1958 Chrysler owners manual that lists 5w20 as one of the recommended grades. [Roll Eyes] This guy is just parroting the old-school thick vs thin line of thinking.
 
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quote:
Originally posted by Ray H: Hmmm... Help me, here, guys - I'm trying to recall which Indy cars ran with 5W-30 last time...
Indy cars, and most engines used in racing applications, use special racing oils without a lot of the additives used to make oils stable and useful for long drain intervals. I, too, would be very interested in learning just what weights are used in various racing applications.
 
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