My fiancee's parents live in St. Thomas, USVI. Her mother has a 2001 Toyota Camry V6: an engine known for sludging up. Severe service in the the VI is the norm. It makes 'severe service' in the USA look like easy midwest driving. Typical driving in the USVI includes extremely steep, curved inclines, which must be taken immediately after startup, steep, curved declines, significant engine braking, high heat, traffic, unknown gasoline quality, etc.
The car overall ran decently, but it did consume oil, occasionally set off the low oil pressure light, showed evidence of sludge and dried oily crud under the oil cap, and smoked heavily at cold startup after the car sat overnight or extended periods. The change from OE specified 5 or 10w-30 to Texaco Ursa surely helped control the situation, but did not help. Per my consulting with yourself and dbdeland, we decided that a metric of number of fuel tanks used was the best way to gauge cleaning, since the extreme hills and extended idling in traffic make MPG numbers irrelevant. Auto-RX was added with the Texaco Ursa oil, and the suggested number of tanks were run. After that, the process was continued in the severe/heavily sludged directions provided, with fuel tanks used being the measurement used the whole time. By the final rinse, consumption had decreased and smoke at startup had gone away completely. Additionally, the oil pressure light has not come back on since, an d the innards as seen through the filler cap appeared cleaner! I wish I had them take oil samples to see what kind of junk, wear metals and whatnot were released in the cleaning process.
They were very impressed with the success of the Auto-RX cleaning cycle, as was I!
J. Heinzel