Castrol 5w-50 is one of the worst oils you can use on any bike that shares engine oil with the transmission.
First, it is NOT a true synthetic like Amsoil, Mobil 1 or Motul, but due to pressure from the Castrol company it was able to take advantage of a loophole and allowed to include the label "Synthetic" for marketing. I will try to find some info on that, as I recently discovered this marketing/legal loophole by accident. Second, that oil has a very high quantity of viscosity improvers, which is one of the first additives to break down under high shear-stress levels as found in motorcycle transmissions. The oil starts life as a 5w oil, and the heavy addition of viscosity improvers (VI) is what allows it to reach 50 weight, at least until it gets some mileage on it. It then rapidly degrades back down to about a 5w20 to 5w30 with use. Most better synthetics have little VI, some like Amsoil have none at all. This means that the base oil is of high quality and can meet the 5w rating at low temps, and 30 rating at high temps, without any VI additives at all. Same for Amsoil 20w-50, no VI additives. Castrol 5w-50 (it used to be known as Syntec in the U.S.) is about as good as a premium petroleum 5w-30 oil, but does not compare in most catagories to even the cheapest true synthetic oil. Due to this legel/marketing loophole, both Mobil and Amsoil are going to start marketing a cheaper "econo-synthetic" or "synthetic blend". The Amsoil XL-7500 formulation (their cheapest oil) will be changed to take advantage of this formulation, and the price lowered significantly to compete with other similar types. Now, dont take this as "buy Amsoil idiot", but rather "avoid Castrol Syntec 5w-50". You would be much better off with Mobil 1, Motul, Amsoil, or any other true synthetic (other than Ams XL-7500) than Castrol. -----Original Message----- From: Sail Kim [mailto:[EMAIL PROTECTED]] Sent: Monday, December 09, 2002 2:08 PM To: [EMAIL PROTECTED] Subject: Re: Amsoil and D220 tires If a bike uses separate engine oil like BMW, Moto Guzzi or HD, light oil make sence. However, for Japanese bike, we need oil to balance engine and transmission need. I use Castrol 5W-50 synthetic on all of my Japanese bikes. >>> "Crisler, Jon" <[EMAIL PROTECTED]> 12/09 10:53 AM >>> Generally speaking, you are absolutely correct. But my example was meant to say that if the application called for a 10w30 oil, and you use a 5w20 oil, or even a 0w10 oil or straight 10w oil, then you should expect higher rates of wear. In a race engine that is rebuilt after every major race, this is factored in to the design and specs of the engine. Further, I read the FAQ in your provided URL, and while generally informative I would have to discount some of what this guy is saying. Also, anybody that recommends straight 30w oil (as in the FAQ) in a street car is seriously out of touch. The last car I ever saw that recommended 30w oil was a 1981 Pontiac Turbo Trans Am (301 turbo), and everybody knows what a POS that engine was..... -----Original Message----- From: Loss, Joe [mailto:[EMAIL PROTECTED]] Sent: Monday, December 09, 2002 1:23 PM To: [EMAIL PROTECTED] Subject: Re: Amsoil and D220 tires It's not correct to assume use of thinner oils equates to higher rates of wear. In fact the reverse can be true. Lubrication is a well-understood science and every application has different optimum lubricant viscosity requirements, depending on the load, surface velocity, clearance and temperature range. See http://www.salemboysauto.com/faqs/faq-29.htm for further explanation. Cheers Joe. -----Original Message----- From: Crisler, Jon [mailto:[EMAIL PROTECTED]] Sent: Monday, December 09, 2002 10:58 AM To: [EMAIL PROTECTED] Subject: Re: Amsoil and D220 tires I can understand why your bike might feel a touch down with a heavier oil. But that is why everybody makes different weight oils. It is a common horsepower trick to use a lighter oil to get a few more HP on race cars, and has long been used by Nascar, F1 and Indy car racing. If you did not like a 15w50 or 20w50, then why not try a 10w40, which is in fact the recommended viscosity. Lighter oils tend to trade higher wear rates for better HP and fuel economy. Both Honda and Ford are going to 5w20 oils for better fuel economy. Oils and engines are getting better, so it is now possible to build a engine that will last 100k miles while using 5w20 oils. But I doubt you could get it to last 200k or 300k.....:) ============================================================================ ========== NOTICE - This communication may contain confidential and privileged information that is for the sole use of the intended recipient. Any viewing, copying or distribution of, or reliance on this message by unintended recipients is strictly prohibited. If you have received this message in error, please notify us immediately by replying to the message and deleting it from your computer. ============================================================================ == The information contained in this e-mail including any attachments may constitute Corvis Corporation Proprietary Information that is subject to Non-Disclosure Agreement and cannot be disclosed to any other party without the express consent of Corvis Corporation. 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