question on oil for 1990
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20 is the viscosity when cold for ease of cranking, 50 is the hot viscosity. Also, Castrol is an excellent dinosaur oil and L98s were designed to run on that type of oil. As far as weight, Castrol 10/40 would be a good choice in your climate unless your engine is burning oil, then the 20/50 might help.
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The recommended lubricant for a 1990 Corvette 5.7L, (engine code 8) engine is 5W30 at all temps. If the temperature never goes below 0 F, 10W30 may be used. The recommended lubricant for a 1990 Corvette 5.7L, 32 valve (engine code J) engine is 10W30 at all temps. In a pinch, if other multi-vis oils are not available and the temperature is always above 39 degrees, straight 30 weight oil may be used in either engine.
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That recommendation is for fuel consumption, not engine service life. As an engine ages and clearances open up a heavier weight oil is often warrented.
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Gee, nowhere in either his post or his profile does it say how many miles are on the car or whether it burns oil or leaks it or that the oil pressure runs low or anything to indicate that a heavier weight oil is "WARRANTED." Also, the gentleman is an offshore oilworker; how much might he drive the car? A lubricant's purpose is to keep the metal surfaces from touching each other and unless the engine is real sloppy 5W30 or 10W30 will work quite well.
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Easy to see how you went thru 19 corvettes, the engines all wore out. :doh:
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Where in hell did you get an ******* remark like that. Although I have had many cars I have had only one Corvette. I keep my cars for a long time and every one of them have had more that 100,000 miles on them and two of them have had over 200,000 miles on them. NONE of them were traded or discarded because of engine problems or oil burning problems. My current DD which I purchased new has 124,000 miles and does not burn a drop of oil between changes.
That said, one of the most important capabilities of lubricating fluid is FLOW, both for lubrication and cooling. Use of a higher viscosity lubricating fluid than the one recommended for the vehicle can inhibit the flow and actually cause premature failures.
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You had it in your profile a while back. I agree that you can go to heavy on oil weight but I also think that a 22 year old engine can benefit from a small bump up in oil weight. That is why I suggested 10/40 when 20/50 was mentioned by Theo. In the end it is up to the individual to decide what oil to use based on running conditions, engine condition, oil cosumption figures, etc......
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If you saw that in a profile you were looking in the WRONG one. Never was in any profile of mine.
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Many "couch" mechanics think they are giving their engines greater "protection" by running heavier grades of oil when in fact they are only increasing frictional drag and increasing oil consumption as the rings have a harder time scraping the excess oil off the cylinder walls.
Unless an engine is being used in a "severe duty" application (such as pulling heavy trailers and operating in severe heat) a 30 weight oil is more than adequate................
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Amazing, when an engine starts using oil I have always been able to reduce blowby and oil consumption by using a heavier grade oil. According to you though the correct thing to do would be to go to a lighter grade oil.
Think I will pass on that revelation..
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in the old days ,oil viscosity was based on weather conditions..look in any GM shop manual from the 70s , you base oil weight on the expected temp of your next change... but with todays multi-grade synthetics, a 10w30 will work in any Corvette motor on the street..I use it in both my LS-1 and my all forged stroker... 5w30 is designed for better fuel mpg in motors with tight clearances .. but I personally find it light for really hot climate ...use a 5w30 in a forged motor, and it will go right thru it. ...20w50 is for severe heat or towing situations ..or air-cooled engines
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