I have used Castrol oil in the engines of the cars I have owned and for topping-up the sumps of road-test cars for as long as I can remember and the only bearing trouble I have experienced has been a “run” big-end on a 1924 12/20 Calthorpe a few years ago, when the engine was already extremely worn. My preference for Castrol stems from the respect I felt as a boy for Sir Charles Cheers Wakefield, founder of the specialised company making this oil, for the manner in which he cheered on the racing drivers, record-breakers and aviators of the time by backing their high-speed exploits, and for the feeling that an oil which got the Alcock and Brown Rolls-Royce Eagle-engined Vickers-Vimy across the Atlantic in 1919 and is used by B.E.A. and the R.A.F. for today’s gas-turbine aircraft, which was specified by Sir Henry Segrave for his 231-m.p.h. record in the Napier-Lion-engined “Golden Arrow” in 1929, used by Fangio when winning so many races for Mercedes-Benz, and by Rauno Aaltonen to enable him to clinch last year’s European Rally Championship in a Mini-Cooper S, must be good enough for the cars I drive.
So I am happy to put my trust in Castrol. Except in those far-away days when one listened with anxiety for a tap in the engine of a £5 Austin 7 which might denote melting white-metal in one of the diminutive big-ends, it has never let me down. A combination of Castrol oil and modern thin-shell engine bearings has made the old nightmare of “run” big-ends and “worn mains” non-recurring.
Why, then, was there need for all this research, culminating in New Formula Castrol, sold in clean-looking, redesigned new tins ? Castrol explain it this way. The ordinary car engine produces more b.h.p. for a given size today than was the case a few years ago—for example, the 1966 Ford Anglia Super develops 48.5 b.h.p. at 4,800 r.p.m. from 1,598 c.c., compared to 36.1 b.h.p. at 4,500 r.p.m. from 1,172 c.c. of the 1958 Anglia—which implies harder work, increased stresses, higher speeds, greater operating temperatures. Couple this with improvements in controllability and tyre-performance of mass-produced cars and the growth of Motorways, which means steadily increasing sustained road speeds, and add the factor of more frequent stop/start driving in modern traffic conditions, and the need for a far more versatile oil becomes apparent, an oil able to cope equally successfully with high-speed, high-temperature pounding and low-temperature working occasioned by frequent short journeys.
In addition, modern design calls for a compact, small-sump engine, yet present-day servicing schedules call for longer and longer periods between sump draining and replenishment. For instance, in 1939 the average small-car sump capacity was around 10 pints; today it is likely to be only half as much. Twenty years ago it was customary to change the engine oil every 1,000 miles; today the drain period may extend to as much as 6,000 miles. In other words, half as much oil has to serve six times as long under far more exacting conditions.
Originally, Castrol, like other oils, was non-additived. In a modern car under prevailing conditions the piston-rings would have stuck fast in their grooves due to high-temperature deposits after some 1,000 miles, the engine would become full of tacky black sludge, lumps of this substance would be liable to lodge in the oilways, starving and ultimately destroying the crankshaft bearings, and at the very best wear on all moving surfaces would be greatly accelerated. After about 20,000 miles the power unit would be reduced to scrap.
For this reason, in 1935 Castrol was the first company in the World to use chemical additives on a commercial scale in a motor oil. These were devised from patented chromium and tin compounds, which gave Castrol anti-oxidant and detergent/idispersant properties. Originally these compounds were able to perform their task only by reacting chemically with the metal surfaces they were designed to protect, but research led to new compounds, the basis of New Formula Castrol, that will combine chemically not with the metal surfaces of the engine but with constituents of another additive in the oil, thus providing powerful localised protection when and where it is needed. In 1938 Castrol introduced “lighter” oils, foreshadowing the modern multigrade lubricants, and in 1949 they were among the first to use a zinc dialkyl dithiophosphate additive as their anti-oxidant. The next major step forward by Castrol technologists was the use of an oil-soluble long chain tertiary alkyl primary amine tungstate additive (British Patent No. 882,295)—lets call it tungsten— which, whenever the stress at a given point in the engine becomes extreme, generates, from within the oil itself, an extra protective compound which exhibits very great friction-reducing and antiwear properties. This is one of the additives used in New Formula Castrol, for which is claimed easier cold starting and better m.p.g. because of the improved deposit control and viscosity characteristics, and greatly reduced wear and a greater safety margin on account of the liquid tungsten, in the case of Castrolite 10W/30, with reduced oil consumption and greater engine cleanliness as well, in the case of Castrol XL 20W/50 which is specified for certain high-output engines and the power units of older cars.
New Formula Castrol was evolved after exhaustive experimenting and testing at the Castrol Research Establishment at Bracknell in Berkshire, described in Motor Sport last November and proved during a 12,000-mile figure-of-eight run in an Austin 1800 using New Formula Castrol XL in Australia, where shade temperatures of up to 122 deg. F. were encountered, in Norway’s Arctic winter in Triumph Herald, Volvo Amazon and VW 1300 cars lubricated with New Formula Castrolite, each of which averaged 1,500 cold-starts at 60-minute intervals, and in a Morris Mini Minor saloon with New Formula Castrol XL in its combined sump and gearbox for 10,000 miles under R.A.C. observation in Central London traffic, day and night, round the clock.
New Formula Castrol is offered at no increase in cost and it is expected to be on sale at all garages, instead of at 80% of them as it was before the Monopolies Commission acted. This Castrol contains the latest and most effective additives known to lubrication technologists, so that those who use it need never bother with squirts of this and shots of that in sump or petrol tank. Indeed, some of these proprietary additives, if used in New Formula Castrol, will undermine some of its qualities, although not doing any actual damage. Nevertheless, it is significant that Castrol consider solid materials unsuitable for inclusion in a motor oil because of the risk of them depositing out, and because such relatively large quantities are required to give adequate protection. Verb. sap.!
To Castrol’s main Research Establishment where the latest oil was evolved has been added a fine Engine Test Laboratory, the 32 test beds of which must be the envy of many car manufacturers. In a spotless, fume-free hall covering approximately 12,000 sq. ft., these test beds enable all manner of power units to be run under every conceivable condition, but notably for long periods under load, while lubrication problems are studied. The equipment includes Lauson, CLR and Petter W1 single-cylinder test engines, and Ford Cortina, Riley 1.5, Standard Vanguard and VW 1200 production power units, on which overall oiling problems, filter-blocking and cam and tappet tests are carried out. Diesel lubricants are investigated in Ruston & Hornsby single-cylinder horizontal c.i. engines, fuel with a high sulphur content being used to test the special sulphur-resisting properties of Castrol diesel lubricants, and two-stroke oils are evaluated in 250-c.c. Ariel Leader, 147-c.c. Villiers and 49-c.c. Motobecane Mobylette engines, while a Commer TS3 engine, which has its test bed in a separate room, is employed to test marine crankcase oils. Much road testing is also undertaken.
Castrol have discovered that specialised areas of ordinary production-car engines, such as tappets, gudgeon-pins and piston rings, etc., are now very close in ordinary service to critical conditions simulated in the laboratory, pointing to the timely introduction of tungsten-additived sump oils. Incidentally, although Castrolite and Castrol XL in their latest forms cover the needs of most car engines, other grades are still made, such as the nostalgic-sounding Castrol-R (which has also benefited down the years from the addition of additives and is especially useful for worm-gear lubrication) and Castrol 98 for gas-turbines.
As I said, I always use Castrol in my cars. I shall continue to do so in future with even greater confidence.—W.B.