We are starting a new test. These things can not be done over night and picking the right car is important. Right car meaning someone driving in a pattern we are looking for and someone that will come in for the oil change at the right mileage.
This is a 4 ounce test. I have some experience with 3 vs 4 ounce doses and in dealing with Frank it appears that 3 ounces is a good maintenance dose but 4 ounces in a 4-5 quart system hits a sweet spot for some additional Auto-Rx benefits, that is friction reduction. We are finding that it is useful to add that extra ounce. It's been true in tests run on a Volvo that is used for a 360 mile a week commute. The car is in very good shape and gained a 5 percent increase in mileage but it took until the end of the second tank of fuel to realize the change. This is another thing that Auto-Rx suffers from. It is not a product that give one instant gratification as claimed by other products. This just may be because there is no such thing as an immediate turn around in cleaning or fuel mileage or friction reduction.
One note about fuel mileage with that Volvo. It was driven to Phoenix from Vista California and back over the week end. 100F and driven with the flow of traffic in the desert at 80-90 mph. Over similar trips last year the car got a 5 percent improvement in mileage at speed with the a/c running full blast. This is a black turbo wagon. This trip has been made at least a dozen times of the past couple of years and the mileage is checked by the driver every trip. This increase was realized over the same car using a 3 ounce maintenance dose.
Again, I think that 4 ounces in a 4-5 quart sump is the sweet spot for the maintenance dose. Auto-Rx does more than just keep the crud down.