I ran Royal Purple when it was marketed as MAX OIL. It was not available to the consumer market, industrial customers only. Brazos Valley Racing began to bottle it in quarts and it sold like hot cakes. With in one year Royal Purple began to market to consumers.
The brains behind Royal Purple and its base formula has been doing synthetics since the 70's. I had seen the ION II brand about the time Mobil 1 came out.
I was getting the good buddy deal, $65 for a 5 gallon pail. When that went away I began to use Mobil 1 as it is available at anyplace that sells oil.
Each one is a fine oil. I decided to go back to AMSOIL as I like the long term drain intervals and AMSOIL markets spin on filters that last 6 months or 12,500 miles. I have run 30K+ miles a year on my truck and Constantly having to change the filters every 3k got real old.
I had used AMSOIL previously but quit when a marketing director at the corporate level put me and several other dealers out of business. He is no longer there. I order on the web and have it shipped to my work.
I keep a log book in my truck when I gas, add oil and do any work. That way I do not have to try and remember when I did something. I got less oil consumption when I went to mobil 1 under the same conditions as Royal Purple. I picked up 0.5 mpg when I went to AMSOIL. That actually supprised me. I put 4400 miles on my truck in the 6 weeks after memorial weekend this year and used 1/2 quart of oil. Considering the engine has 221K miles on it, I think using synthetic oil has done me well.
When I first used AMSOIL in 1983, I put it in an S10 with the 2.8 L V6. I gained 22% increase in mileage. In my present truck, I gained 15% in mileage imporvement. When you calculate the cost of the oil, how much money is saved at the gas pump, synthetic oil has proven to be FREE and puts a couple extra $$ in my pocket.
I pull my oil fil plug and show folks the shiny metal underneath the light oil film on the rocker. I am just now begining to show some weepage at the rear main seal which when you consider the mileage on the engine aint too shabby.