To Whom it may concern,
I've used Amsoil Synthetic for over 15 years in various autos and all the motorcycles I've owned with no problems or any type of grief.
To answer previous questions asked I submit the following Amsoil data:
Amsoil recomends changing engine oil at 1 year or 25,000 miles.
There is a good deal of test data available of cross country truckers that have gone over 100,00 miles with an Amsoil bi-pass filter and no oil changes.
Change the normal oil filter every six months. They recommend Amsoil filters as they are designed for extended service.
Warrentee void claims by dealers are commented on by Amsoil on their webpage and written data saying that warrentees are fully supported by auto manufactures and Amsoil itself. Along with this they state they will provide legal data and support should anyone find a dealer attempting to invalidate a warrentee based on frequency of oil changes or the use of a synthetic.
Amsoil provides much information concerning testing done by independent testers as to the performance of Amsoil versus any other synthetic or petroleum based lubricant available.
End of Amsoil data.
My independent auto service tech told me post a valve adjustment on a 1989 Honda Accord LX-I that the internals of the engine were surprisingly clean for an engine with 125,000+ miles. "It looks like new" was the quote.
Many other synthetics have value but not the long term change interval nor the type of protection under high temperature and performance demands of many engines. See Amsoil data at http://www.amsoil.com
for specifics on all of their wide range of products.
The only thing I don't particularly like is that Amsoil is a network marketing organization. In their favor they do NOT use a scheme that makes only the very top rich and all other poor.
I'm on the waiting list for a 2006 Prius and will change to Amsoil after about 5,000 miles to allow for engine break-in.