Oil viscosities - general recommendations?

It's been explained to me that these days the new cars are requiring a 5W30 or a 10W30, and I think some might even require a 5W20, but I don't know which
cars those are. My question is, are the older guidelines for single grade oils pretty much the same: sae 30 for temperatures around 40 or above- etc.? I can't remember exactly what the temperature cut-off ranges are. I've got 5 gallons of sae 20W that I plan on using during the 2nd quarter of the year: March - June. The two vehicles that I currently have are a '93 GMC Safari Van, and an '03 Chevy S10. Also, I have a bunch of 10W40 which I guess I can use during the hottest months- at least in the van. I'm very interested in hearing all about this stuff from those of you who have the answsers. Thanks, Dale snipped-for-privacy@aol.com
TeleDale Key Service, http://www.angelfire.com/wizard/teledale 1811 Saratoga Avenue, Cleveland, Ohio 44109 U.S.A.
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On 12 Dec 2004 08:42:36 GMT, snipped-for-privacy@aol.com (TeleDale) wrote:

go to www.bobistheoilguy.com and do some reading. SAE20 isn't appropriate for ANY automotive application. Ford is the only one using a 5W20, and it's spec for the oil is a very stout synthetic package. just use what the manufacturor specs and you'll not be risking your engine.
-Bret
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| >:| | >:| | >:|TeleDale Key Service, | >:|http://www.angelfire.com/wizard/teledale | >:|1811 Saratoga Avenue, Cleveland, Ohio 44109 U.S.A. | | go to www.bobistheoilguy.com and do some reading. SAE20 isn't | appropriate for ANY automotive application. Ford is the only one | using a 5W20, and it's spec for the oil is a very stout synthetic | package. just use what the manufacturor specs and you'll not be | risking your engine. | | -Bret
Chrysler and Honda also spec 5W20 for some applications. There may be others. It's not just Ford recommending 5W20 viscosity oil.
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That's correct, I read the only reason that they specify that oil weight is to make their fuel mileage numbers.
Brian
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Another good site: http://www.chris-longhurst.com/carbibles/engineoil_bible.html
I would dump the 10W40. Read the sections about Viscosity Improvers. They can be really hard on your engine.
Straight 20 is probably OK. Many years ago I remember a guy, who was a district representative for an oil company, that used nothing but straight 10 weight all year. He put on a lot of hard miles. I guess I would dispose of all of it, but I am biased as I won't use anything but synthetic in my engines (including and especially air cooled mowers, snow blowers and generators).
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Thanks to all who responded. I will look at those web pages. Dale
TeleDale Key Service, http://www.angelfire.com/wizard/teledale 1811 Saratoga Avenue, Cleveland, Ohio 44109 U.S.A.
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