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Auto-Rx in Bentley & Rolls Royce

My car is a 1983 Rolls Royce Silver Spur, 6.7LV-8. 67,000 miles, 10-quart oil capacity. It has a ticking sound (comes and goes) that is indicative of a sticking lifter or possibly a partially plugged oil tube. Your plan for the cleaning phase says to add Auto-Rx® and drive 3,000 miles, then change the oil/filter out. (I plan on using Royal Purple 10-40w after the cleaning phase.) Here are my questions about using Auto-Rx®:

  1. Since the engine uses 10 qts of oil, should I add MORE Auto-Rx® during the cleaning phase (maybe 16 oz total to maintain the ratio)?
  2. Since I only drive the car about 3K total per year (at 10 MPG, can’t afford to drive it too much), should I go with the whole 3K/one-year period for the cleaning phase, or run it a shorter amount of miles and then change out to the Royal Purple?

I have used Auto-Rx® in several 1984-1994 Rolls and Bentleys. In one case I added two bottles to the oil. I did not notice that it cleaned any better than just using one bottle. I kept mileage records on all five cars before and after the cleanings. On the highway at 70 mph on cruise, my 1984 Spur got about 10 miles/gallon before cleaning and improved to about 12 miles/gallon after the cleaning. That engine had 84,000 miles on it when I started the cleaning.

I strongly suggest that you drive the car at least twice a week for some errands after letting it warm up to full temperature. I have owned over 70 of these cars since the early 1970s. They absolutely hate not to be driven. What you are saving in gas will be spent in maintenance you could avoid simply by driving the car regularly. I have always used Castrol 20/50 in my cars and recommend it highly. Whatever you use, I can tell you that, for some reason, these cars (except for the very new ones) do not like synthetic oil.

One other serious hint (it is in the owner’s manual but most people overlook it): The proper way to check the coolant level in the cars 1980-1997 is to turn the heat up to max and have it blowing on the windscreen, let the car get nice and hot, and then turn off the car without changing the A/C control settings. Let the car completely cool and then check your coolant levels. The reason is that an air bubble frequently forms in the heater coils which are higher than the rest of the coolant system. Leaving the system hot and open forces water to stay in the coils.

It is common for these cars to show a full coolant reservoir when improperly checked and the temperature gauge will give you no clue that your car is running hot—even to the point of radiator damage. The only warning you’ll get is a check engine light without a lot of time to stop. Most Rolls mechanics that are not factory trained overlook this problem.

Good luck with your car! If you drive it enough to get really used to it, you won’t want to drive much else. In 1992 they came out with a transmission with an overdrive. My ’94 Bentley Brooklands LWB gets 18miles/gallon at 80 on cruise.

—James M.