Amsoil against 5-20W?

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Sep 17, 2003
A little over a year ago Amsoil had an article about 5-20W on their web page. They warned against Ford and Honda owners using 5-20W. They stated something about the auto companies making the switch to save gas mileage in the mass amount of vehicles they sell every year. I can't find the article now. Is it gone? What happened? After reading the article I convinced my bro. to stop using 5-20W in his stang. Can anyone shed some light on this?
Mobil's first synthetic was a 0w-20. Modern engines are fine running on 20wt oils, if there made right. One of the most controversial debates on this website is the "thick vs thin" viscosity debate. The answer is, it depends on your engine. There has been no proof on here that viscosity is that relevent to wear other then certain engines, with varying clearances, call for thicker oils, such as the LS1 and Jeep 4.0L. For racing conditions or Turbos you would want an oil that is thick enough to provide the right amount of protection, and thin enough to have great flow. The whole arguement is really that simple in my opinion. CAFE plays a huge role but certain engines today are fine on 20wts I believe. I could be wrong and I'm no expert but the information I've read from people who know this stuff, suggests 20wts are fine for most cars. It really depends on the engine your dealing with. Corvette's run on Mobil 1 5w-30, and have for years. Mobil 1 is not the best oil for this engine as it is a bit too thin. However, there are many, many people with LS1 engines that have well over 150k miles on them using Mobil 1. Some of them ran on the Mobil 1 that was even closer to a 20wt oil!! So while it's not the best choice, it has shown to be good enough. Maybe your LS1 would last 500K on a thicker oil such as Amsoil...who knows....I know that no one keeps Vettes that long to find out so it really doesn't matter. Also remember that Amsoil is in the market for extended drains. I spoke with someone from Amsoil and his biggest concern was having a 20wt oil go for extended drains. [ October 03, 2003, 07:15 PM: Message edited by: buster ]
I don't remember the exact article - but they have spoken against 5w-20 in cars that don't require it (makes sense) and they have spoken against petroleum 5W-20's (but that is funny because Amsoil's XL 5w-20 is Group III) I personally don't like 5W-20. I am 100% sure some cars will have zero problems with it, but the same cars could be even better on a good synthetic 5W-30.
Pablo made a point I wanted to add and that is engine clearances havn't changed so I wouldnt even bother running a 20wt oil. Stick with a 30wt. My point was that a decent 20wt will be fine IMO>
Buster-- Minor correction. Mobil's first synthetic was a 5W-20, about 25 years ago. Reformulated a short time later as a 5W-30, partly for general acceptance and partly because the original formulation caused some seals to shrink.
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