Interesting oil find - old Castrol with Tungsten!

[addyguy]

I was in at the shop yesterday having a coolant flush and oil change done on my car. While waiting for my car, I was looking around the shop, and I saw on an ornamental shelf two very old cans of motor oil. According to the guy behind the counter, a regular customer had found them in his garage, and thought the garage would like them as an interesting display item. They were cans of Castrol 20W-50, with service ML-MM-MS, so they were probably at least 40 years old, but still full. The thing that caught by eye was the inscription on the can was "high-performance motor oil formulated with liquid tungsten for maximum protection". I've never heard of tungsten being used in oil before, must be a very old thing. I guess it was used to increase the high-temp. properties of the oil, because in looking it up, I found this out about Tungsten: "Tungsten chemical compounds are used in catalysts, inorganic pigments, and tungsten disulfide high-temperature lubricants which is stable to 500 °C (930 °F)". Any one else heard of this or ever used oil with this in it? Is it still ever used?

 

[Gurkha]

They used to sell this till the early 80s here in India and since it was the only high performance oil available then, it was used extensively.

 

[Kestas]

It's a good solid lubricant, but it's potentially more corrosive on bearing surfaces than MoS2. http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic;f=5;t=004045 http://www.lowerfriction.com/

 

[GMorg]

Wasn't there some sort of lawsuit between a European car manufacturer and Castrol over gray sludge due to "liquid tungsten?"

 

[addyguy]

I read that too.....Mercedes, I think, sued Castrol in the 1970's(?) over this..... Interesting stuff! Thanks for the links!

 

[Vilan]

You're right about being used at high temperatures. Tungsten has a higher melting point than any other element, over 3000* C. But no car engine should get anywhere near that, so I imagine it has some other purpose.

 

[ekpolk]

quote:

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Originally posted by Vilan: You're right about being used at high temperatures. Tungsten has a higher melting point than any other element, over 3000* C. But no car engine should get anywhere near that, so I imagine it has some other purpose.

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Vilan gets the "Understatement of the Day" award! It would indeed be interesting to see what would happen to a standard issue automobile piston engine if temperatures inside it got anywhere near 3000*C.

 

[Lazy JW]

I have brazed maybe a million tungsten carbide saw tips onto circular saws over tha past 25 years. They won't melt from the heat of an oxy-acetylene torch, I have tried though. Sure doesn't sound like something I would want in my oil though. Joe

 

[Vilan]

quote:

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Originally posted by ekpolk: It would indeed be interesting to see what would happen to a standard issue automobile piston engine if temperatures inside it got anywhere near 3000*C.

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I believe the technical term is .

 

[Kestas]

Vilan, don't confuse tungsten with tungsten disulfide, which is the compound being discussed here. The melting point of tungsten has nothing to do with the material properties of tungsten disulfide.

 

[Vilan]

Very true. My point is that tungsten is high-melting, which contributes to WS2 being pretty high-melting also... stable to 500*C, addyguy says.

 

[sidney004]

When I was a practicing mechanical engineer in the early eighties working in the aerospace industry; we used machinable tungsten counterweights in guidance systems to correct CG imbalances. These were typically mounted on anodized Aluminum. This was the most highly corrosive combination I have ever encountered. A greenish craplike substance eventually resulted in a major redesign. I would hope that the properties of Tungsten Disulphide are orders of magnitude more inert. I would be hesitant to put any Tungsten compound in anything but a glass vial.

 

[Tree Hugger]

I used Castrol with 'liquid Tungsten' in England in the late '60's. One of my friends wrote to Castrol about 'liquid tungsten' (Undergrad Chem Student) and received a courteous reply that it was actually 'oil-soluble long chain tertiary alkyl primary amine tungstates' rather than liquid metallic tungsten.

 

[pscholte]

I used it once in the late 60s and when I had the guy at Shell change it out, and I told him what it cost, he mentioned he might take my used oil and put it in his vehicle...

 

[edhackett]

I used this oil a few times in the mid 70s in my first car, a 1973 Toyota Corolla SR5, the first 5 speed. I remember that it had a rather unpleasant smell and feel if you got it on your hands. I also didn't care for the way the engine felt while using this oil. I used it a few times, but moved on to something else. The oil was clear, maybe a bit darker than most, so it did not use a solid form of tungsten such as WS2. It was a soluble organic form, as mentioned in Tree Hugger's post. Ed

 

[JHZR2]

OT: is that why toyota uses the SR5 designation as an option package on some of their vehicles - because originally it documented the fact that the vehicle had 5 speeds instead of 4 or 3? JMH

 

[Jimbo]

quote:

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Originally posted by sidney004: When I was a practicing mechanical engineer in the early eighties working in the aerospace industry; we used machinable tungsten counterweights in guidance systems to correct CG imbalances. These were typically mounted on anodized Aluminum. This was the most highly corrosive combination I have ever encountered. A greenish craplike substance eventually resulted in a major redesign. I would hope that the properties of Tungsten Disulphide are orders of magnitude more inert. I would be hesitant to put any Tungsten compound in anything but a glass vial.

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That finally explains it! When I used to tear down VW engines in that ran Castrol in the 1970s, there were greenish deposits on the undersides of the pistons that looked like the result of some kind of acidic corrosion. As noted in an earlier post, there was also an unusual amount of light grey sludge in the bottom of the crankcase. Pennzoil or Valvoline never left these types of deposits.