MULTIGRADE OILS EVERYTHING YOU NEED TO KNOW
Born ‘slippy’, Fuzz Townshend explains how contact is kept to a minimum
Many years ago, when motor cars were whimsical toys for well-heeled society players, the oil industry was somewhat in its infancy. Yes, steam propulsion had needed lubricants, but the internal combustion engine brought with it different requirements for its oils.
Very quickly, most of the moving parts within internal combustion engines became encased, hidden from view; and so, it became that the lubricant was retained within, rather than being constantly added by a bloke with an oil can.
Such containment meant that the oil had to be in a known condition for a suitable amount of time, for peace of mind when the engine was in use. A very good lubricant in the earliest days of motoring was castor oil… castoroil… Castrol… geddit?
Anyway, this stuff did the business, but only for short operating spans; it needed to be changed after a few hours of use as it was prone to chemical breakdown, losing its lubricating efficacy along the way.
So oil firms began working on suitable lubricants with greater longevity and by mixing base oil with other Petro-chemical and other products, and monograde oil with a longer service life became available.
Monograde oil was fine, but it had a limited window of efficiency when it came to environmental operating temperatures and to the ever-diminishing tolerances between moving parts within modern engines. This meant seasonal engine oil changes were common well into the 1960s and beyond.
However, oil was being changed not because of its condition. It often had plenty of life left in it and, sometimes, old oil was recycled in centrifuges and through filters, chemically tweaked and put back onto shelves as a cheap brand.
Summer and winter changes were wasteful and a bit of a pain. What was needed was an oil which could be left in place to do its work until spent; enter multi-grade oils.
Multi-grade oils had the ability to act like a thinner, ‘winter’ grade
’Oil had to be in a known condition for a suitable amount of time’
oil ( grades 0 to 25) in very cold conditions, but then encompassing the abilities of ‘summer’ grade oils ( grades 30 to 70) as operating conditions warmed up.
This saw oil change frequencies plummet, and with further development, oil changes crept up from low thousands of miles, through 5000 and well beyond into double figures, given adequate filtration.
Multi-grade oils for cars without filtration, such as vintage machines, were and are also available but change frequencies on a mileage basis remain high, thus often negating the need for an all-seasons lubricant.
Multi-grade engine oils are far more sophisticated than simply being able to operate through different seasons; for instance, the relatively high revolutions per minute of even some of the most ancient engines can cause the oil to froth up.
Such aeration of oil would result in little or no supporting ‘ barrier’ film of oil between any given adjacent components, leading to them rubbing together and so rapid mechanical failure.
As a personal reminder of the significance of decent oil, when I was a 16-yearold apprentice, a rather creepy garage supervisor sidled up to me as I idled away my time waiting for my skilled craftsperson to return from a dinner break. Through thick glasses, he eyed me and said: ‘ Young man, do you know the most important word in engineering?’
Says I: ‘No.’ He leaned into my ear and growled lasciviously: ‘Lubrication.’