I had never heard of Auto-Rx^® until a friend of a friend told me that Frank Miller, the creator of Auto-Rx^®, wanted to conduct a comprehensive test of his product, including oil analysis, in a high-mileage motorcycle. I was asked if I knew anyone who owns a motorcycle with a lot of miles on the odometer, preferably a motorcycle that had not received the best of care. Failing to find such a motorcycle among my friends who ride, I agreed to use my own motorcycle, a 1996 Suzuki RF900R with 59,085 miles on the odometer at the time, as the test subject. This motorcycle has unit construction in common with many other machines on the road; the engine, transmission, and clutch all share the same lubricating oil, a feature that I believed would have no relevance during the test.

I was approached because I am a motorcyclist who maintains his own machine, and because I am not affiliated with any motorcycle brand or manufacturer, nor any motorcycling publication or advertiser. I have been riding motorcycles for 32 years and have maintained my own machines, and those of my friends, from the very beginning. As for any formal maintenance training, I am a licensed aircraft mechanic with both airframe and powerplant mechanic licenses. I also fly and hold a commercial pilot license.

It was explained to me that Auto-Rx^® is not a quick-acting solvent, but rather a metal cleaner that works over an extended period of time. I was skeptical that my machine would benefit from the use of Auto-Rx^®, as my motorcycle engine was already quite clean and always received the very best care and preventive maintenance necessary to keep it that way. I did not believe Auto-Rx^® would have any effect on a clean engine.

The directions for using Auto-Rx^® to treat an engine are simple and easily accomplished. Auto-Rx^® may be added to the engine oil if it has at least 1500 miles to go before the next oil change, or Auto-Rx^® may be added to fresh oil; in either case a new oil filter should be installed. Auto-Rx^® may be added to either mineral or synthetic oil for the cleaning phase; however, mineral oil is recommended for the rinse phase.

During the test of Auto-Rx^® in my motorcycle, I followed these directions exactly, paying close attention to mileage intervals. Because oil analysis would be performed on oil samples drawn during each phase of the test, there would be some variation to the Auto-Rx^® application procedure that would otherwise not be necessary. Because the rinse phase calls for mineral oil, I used mineral oil throughout the test for the purpose of consistency in comparing one oil sample to another. Because my motorcycle had been using synthetic oil, a change to mineral oil for at least 200 miles to flush the engine was performed, followed by a 2000-mile pre-test interval to establish an oil analysis baseline for my engine. The oil was then changed again for the Auto-Rx^® cleaning phase as suggested in the instructions, followed by a change for the rinse phase; the engine was returned to synthetic oil after the end of the rinse phase. A new oil filter was installed at each oil change.

Oil samples were drawn after the 2000-mile pretest interval, odometer reading 61,300 miles; after 1000 miles during the cleaning phase, odometer reading 62,300 miles; at the end of the 1500-mile cleaning phase, odometer reading 62,800 miles; after the 2000-mile rinse phase, odometer reading 64,800 miles; and 2000 miles after returning to synthetic oil with an odometer reading of 66,800 miles. The 1000-mile and 1500-mile cleaning phase samples would be compared to each other to help determine if motorcycles should use the same cleaning phase interval as automobiles.

In addition to oil samples for analysis, engine compression readings were taken at the end of the pretest, cleaning, rinse, and 2000-mile post-rinse intervals; I was told to expect dramatic increases in engine compression after my engine was cleaned by Auto-Rx^®.

I believe my motorcycle to be well maintained, yet otherwise average. From the day I took delivery of my then brand new motorcycle, I have followed Suzuki’s recommended maintenance schedule. It has always had its oil changed regularly using only the highest quality oil products, and its oil filter changed every time the oil was changed. Originally broken in using mineral oil, it was later given a semi-synthetic oil blend, and for many miles now has operated with fully synthetic oil in the engine sump. Tires were never allowed to wear completely slick; chain and sprockets were always changed as a set, etc. Anything my motorcycle needed, it received, especially attention to detail. I always believed a well-maintained machine would not benefit from the use of a product such as Auto-Rx^®; in my opinion a machine that showed improvement after treatment was a machine that needed more than just some product added to the engine oil.

So, now that the test is over, what do I think of Auto-Rx^®? My first impression was one of indifference; I never felt any seat-of-the-pants improvement in the engine’s performance. While no dynamometer runs were ever conducted, I know my motorcycle well enough that I can feel small changes such as the difference in how my machine performs on a cool, dry day versus a warm, humid day. Not feeling any seat-of-the-pants improvement mirrored the lack of change in compression readings from phase to phase, with only minor variations of one psi here or two psi there that could be attributed to anything from ambient conditions, to how the motorcycle was ridden immediately before the compression readings were taken, to the compression gauge itself; the same compression gauge was used throughout the test. A lack of change in compression readings would seem to indicate that the piston rings and their respective ring grooves were clean and free of any carbon or other deposits, thus able to function as designed before the Auto-Rx^® application; with nothing to clean, there was no performance improvement.

The oil analysis results were another matter entirely. These results indicated that something was indeed happening. While oil analysis showed that my motorcycle has a very clean engine, it also showed that Auto-Rx^® did work as advertised, albeit not as dramatically as the early predictions claimed.

The pretest oil sample analysis showed a clean engine, but analysis of the two Auto-Rx^® cleaning phase oil samples indicated elevated levels of the various metals and materials the oil analysis process detects; analyzing the remaining oil samples indicated these levels fell somewhat during the rinse phase, followed by post-test phase levels returning to near pre-test standards. Identifying the metals indicated their origins; whether from the pistons, piston rings, cylinders, engine bearings, or other engine components, the presence of these metals in the oil is the result of over 60,000 miles of wear and illustrates that regular oil changes cannot actually clean internal engine components.

Oil analysis also showed a surprising amount of the material removed by Auto-Rx^® came from the transmission and the clutch, a result I had not anticipated. Had the clutch cover or oil pan been removed at this mileage without having ever used Auto-Rx^®, and if inspection of these areas revealed no cause for further disassembly, the absence of visible sludge or sediment deposits within the engine cases that could be inspected from those points would have resulted in no further maintenance action, replacing the covers, and giving the engine a clean bill of health. It became apparent to me that Auto-Rx^® worked at all levels, from scavenging and removing visible contamination, cleaning all metal within the engine cases, to removing contaminating material not necessarily visible to the naked eye.

Even with these results, it was still gratifying to read the comments of the person performing the oil analysis, noting that my engine was remarkably clean right from the start. This comment, in my opinion, shows what a good, regular extended engine performance program can do for any machine. However, the oil analysis shows that even the best maintenance can fall short of keeping an engine completely clean internally.

My conclusion? In addition to a regular extended engine performance program, the use of Auto-Rx^® on at least an occasional basis would benefit any motorcyclist wishing to ensure that his or her motorcycle will operate at peak efficiency for many years to come.