Oil for the ’54 Brake Vacuum Pump
Ken Laytin BCA #30473
For those of us whose ’54 Buicks have a Moraine or Trico vacuum pump designed to supply the power brake booster with vacuum should the engine quit while the car is moving, a question comes up over and over. What kind of oil goes into the pump’s little reservoir? If you have disassembled one of these units, they are quite simple. The electric motor rotates a shaft inside the pump chamber, which is just a short, out of round cylinder. On that shaft inside the chamber at 180 degrees from one another are two vanes, looking like small generator brushes. Each vane can move in and out, but is spring loaded so that it is always pushed out against the wall of the chamber as it rotates around the chamber. Since the unit is out of round, the size of the chamber the vanes create gets larger and smaller as they go around. This creates the vacuum. But something needs to lubricate the vanes so that they do not get rapidly worn away as they scrape the chamber wall and something needs to help them seal against the wall as they go around. That is the job of the oil. The reservoir mounted above delivers oil into the pump chamber via a wick, dripping tiny amounts in, very slowly. The Buick parts book appears to say that the oil is “Stanotorque oil”. The problem is that finding any of this oil is like winning the lottery. It was apparently made by Standard Oil of Indiana, long since incorporated into other companies and now BP. No help there.
With the original oil no longer available, I’ve seen discussions suggesting using motor oil, 3 in 1 sewing machine oil or air compressor tool oil in its place. No one seems to know for sure which is correct. A few years ago I decided to research it. The pump in my Buick was made by Trico. Long story short, I actually tracked down two old-timers who had worked for Trico in the 50’s and 60’s. They both remembered the pumps, but not the oil that went into it. Dead end. More recently I was asked the question about the oil once again, this time by a fine gentleman and club member in NC named Conrad. I decided to resume my research. Besides the question of what type of oil, there was the obvious question of what weight or viscosity oil. Since it enters the pump via a wick, oil too thin or too thick would mean too much oil or too little oil. I started by talking to companies that make wicks, not for candles but for vacuum pumps, since some modern pumps still use a wick delivery system for lubrication. Everyone I talked with tried to help, but basically explained that they were experts with wicks, not the oil. Then I thought perhaps I could spare a little of the original oil still in my pump and have it analyzed to find out what it is. I came upon a company that analyzes oil, that oddly enough is called Trico Corporation. The company is in Wisconsin and not at all related to the company that made the pumps originally or makes today’s wiper blades. They just have the same name. Trying to be very helpful, they transferred me their chemical engineer, Weston Griffis. On the phone, Wes gave me a lubrication 101 course and thought he might be able to find out what that oil was. But he said that if not, his research would determine what we should use in the pumps as an equivalent. He knew what composition the oils of the 1950’s were and what the requirements of our pumps would have been. He explained that the oil needed to be slightly compressible or contain additives that were so that the vanes would seal against the pump body. He promised to get back to me.
Sure enough, a couple of days later Wes called me. The answer he provided is Mobil DTE Heavy oil. It is a mineral based oil 100 ISO grade with additives like phosphate and zinc to do the sealing. He says it should be fully compatible with any original oil still in the pump. You can find this oil online. Although we only need a few onces, I could only find gallons. The best price was at Walmart, for about $28. per gallon. I haven’t tried it yet and obviously none of us want to risk destroying these rare and rather odd brake vacuum pumps. There is of course no guarantee that he is correct. But after talking with him, his expertise was obvious. He left me impressed and confident about which oil to use. He also left me very appreciative. It’s interesting how many fine people there are who are willing to use their time to help us keep old Buicks on the road.
Two other (non-oil) recommendations related to these pumps. They have a tendency to seize up if not run often. When the vanes have not moved in a while, the oil causes them to stick to the pump wall and refuse to rotate. That can burn up the motor very quickly. Sometimes a gentle rubber hammer tap on the pump body when the key is on gets it going. If not, just disassemble and reassemble the unit. But a better plan is to turn the key up (without starting the car) and run the pump for 10 seconds every week or two, if the car is stored. It’s also a good idea to put a switch between the pump and the fuse panel that allows you to temporarily disable the pump if you are working on the electrical system and need the key on. The pumps have a small motor that can burn out since they were not designed to run continuously for long periods.