Im a Volvo Resto Man Id say I service the cars I restore with Auto-Rx about 80% of the time before they leave. I also recommend it to my service customers. Most recently, a customer brought me her 1990 244 to be refurbished. The car was exhibiting some oil loss from the rear main seal. Part of the service included an oil change with our favorite elixir. When the car came back for the follow-up about 2,000 miles later, the bell housing and surrounding areas were completely dry, no sign of the leak at all. Not the first time Ive had these results. Ive stopped leaks at cam and intermediate shaft seals, crank front seals, too. The red block 240s are often plagued with gummy piston rings from lack of high speed use or poor oil change upkeep. This leads to piston slap. Using Auto-Rx cleans the piston rings and quiets the engines. I find that following the maintenance routine also keeps the Volvo flame trap system clear, very important in these cars.
