ANOTHER ARTICLE ON CHLORINATED PARAFFINS:
John Rowland, Derby
[John is an industrial chemist with vast experience in the field of lubricants.
He wrote this item more than a year ago, but somehow it buried itself
beneath a layer of e-mails and went unnoticed. Its time has now come.]
Dave Pittuck came across the publicity for a lubricant additive named Bitron, for which some wonderful claims were being made, and he asked me whether it was likely to of benefit to Morgan owners. I told him not to touch it with a bargepole. At about the same time I was contacted by a French acquaintance who had put the additive Mecacyl in the gearbox of his Citroen tintop and subsequently discovered a great deal of internal corrosion.
Both these products are based on chemicals known as chlorinated paraffins. We oil industry types knew all about chlorinated paraffins seventy years ago, and so did the motor industry. Bitron—in common with many other ‘miracle’ additives—is based upon this1930s technology. Chlorinated paraffins have powerful anti-seize properties, so they were used in the early ‘hypoid’ axle oils until less corrosive compounds were synthesised. In the laboratory they give spectacular results in seizure-test machines which look very impressive, but they now only feature in the cutting oils used for the heavy machining of tough steels; there are no automotive applications for them. In particular, they severely corrode copper-based alloys. Those early hypoid gear lubricants which contained chlorinated paraffins could only be used on totally copper-free devices, hence warnings about using them on the bronze wormwheels of Morgans. Chlorinated compounds can also attack iron and steel at high temperatures. (Easily reached around piston rings, for example.)
As EP (extreme pressure) anti-seize agents their mechanism of action is as follows: When two steel surfaces (such as gear teeth) come into contact at high pressure, tiny areas literally weld themselves together. The welded contacts are ripped off the teeth as they move apart;the common name for this process is ‘wear’! Chlorinated compounds decompose due to high temperatures at points of high-pressure contact, generating layers of soft ferric chloride, which prevent welding. The trouble is that ferric chloride in the presence of even tiny amounts of moisture breaks down to produce hydrochloric acid, which eats into the steel to produce more ferric chloride, which . . . etc etc! The stuff attacks copper alloys at a ferocious rate, and the resulting copper salts act as oxidation catalysts which accelerate oil breakdown. Two vicious circles foe the price of one! (Note that the electronics industry uses ferric chloride solution to dissolve copper from printed circuits. Metallurgists use it to etch stainless steel.)
Since around 1960, therefore, the EP agents in gear oils have been safe and non-corrosive sulphur/phosphorus compounds. Chlorinated paraffins have never been used by any responsible manufacturer in engine oils.
The chlorinated paraffins used in industrial cutting oils are fairly stable, and they are always used with an anti-corrosion additive, but they are never used to cut copper alloys, and they are only necessary for difficult jobs. The Health and Safety warnings we have to issue are rather severe, and there are moves to get rid of these compounds altogether. Oddly enough, the correct warnings never appear on ‘magic additives’, and the distributors, when asked if their products contain chlorinated compounds, say ‘no’ or ‘eh?’. One simple way to find out is to pour a drop into water; if is sinks, it’s chlorinated. (Some of the hydrogen atoms in paraffin are replaced by heavy chlorine atoms, so the density almost doubles.) This doesn’t always work if the stuff is diluted with solvents, so try this one: (Perfectly safe for Morgan drivers, skilled in all dark arts, but watch out if you are a muggle.) Heat a bit of thick, clean copper wire to red heat in a gas flame. Contrary to popular belief, the flame will not turn green! Dip it in the suspect fluid, then heat it up again. If chlorine is present, the flame will turn green, due to the formation of copper chloride. (Much cheaper than our infra-red spectrophotometer!)
Incidentally, chlorinated paraffins are also cheap—around £1 per kg in bulk—which means that the purveyors of miracle lubricants are selling the stuff at a mark-up of at least 1000%. The marketers often don’t know what is in the bottle! They are at the bottom of a ‘pyramid’ sales scam, and they can only repeat the nonsense they have been told. Their publicity implies ‘secret’ knowledge that the bona fide lubricants industry is unaware of. Well! What a nerve!
