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A guide to oils for classics

The Classic Choice Published: 9th Jun 2011 - 0 Comments - Be the first, contribute now!

A guide to oils for classics Frequently replacing the oil and filter on your classic is one of the simplest jobs you can do - and one of the most worthwhile
A guide to oils for classics The classic oil scene has grown of late and now there are even advanced brews for motorsport use (left). Pricey but they offer top protection
A guide to oils for classics This is what really counts with any oil - these specs! Many lower cost brands may also boast same quality
A guide to oils for classics New from Comma is a range of special oils to suit classics up to almost 70 years old. Castrol, Duckhams also offer similar ranges
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As yet another major mainstream oil producer launches a classic oil range, we show why such dedicated lubricants are vital for older vehicles… and how you can kill your classic with kindness

It’s strange but true; use a modern, highly advanced and highly expensive super-duper engine oil in your classicand you’ll do your pride and joy more harm than good! There are over 100 different brands and blends of engine oil on sale and it’s easy to use the wrong oil in your car. So specialised are some of today’s lubricants that they even have their own part number at main dealers. In fact, use the wrong oil on some moderns and you’ll invalidate the manufacturer’s warranty! Many motorists and even professional mechanics fail to fully appreciate a lubricant’s role, while it’s reckoned that perhaps one in every four cars run around with dangerously low oil levels too. Ignorance certainly isn’t bliss!

Code cracking

Check out any good quality pack of oil and you’ll see a lot of numbers and letters, which to the uninitiated looks confusing yet in fact not only is this code easy to crack, but it also puts you on the right road to obtaining the right oil for your car, be it classic or modern. A pair of respected independent authorities control lubricant quality. The best known is the still the American Petroleum Institute (API), which has been around since God was a boy and classifies quality alphabetically. On a pack of oil you’ll see S (for Spark) labelling for petrol engines and C (for Compression) on diesels. Currently “SL” is the highest API listing, but you can still find many cheaper alternatives brandishing SF approval, a standard that dates back to the 1970s. Essentially the higher up the alphabet rating, the better it generally is. But you can use an oil that’s too good for a classic - as we’ll show later. The other quality assessor is the tougher European standard entitled ACEA. This stands for Association des Constructeurs European d’Automobiles and it replaced the old CCMC (Committee of Common Market Constructors) body during the 1990s. ACEA ranks oil quality from A1/B1 to the highest A/B3/4 ranking (A standing for petrol, B for diesel, incidentally). Look out also for listed approvals from leading manufacturers; it is reckoned that the Germans (BMW, VW, Audi, Mercedes and Porsche) are the fussiest and as a result their rubber stamps are highly valued on an oil pack. It’s as well to use this credo with oils: no markings = no good!

Make the grade

An oil’s grading is as crucial as its quality and many modern oils are totally unsuited to old classics for this very reason. Today’s precision-made power units work on such tight manufacturing tolerances that that they require lubricants as thin as water for a proper flow; a treacle-like old school 20W/50 would block the oilways in no time. In contrast, use a watery-thin synthetic in an elderly engine designed with its wider working tolerances (and perhaps more than a little worn into the bargain) and you’ll probably sufferfrom dangerously low oil pressure and excessive oil loss due to burning at the piston rings.

Go Classic!

The upsurge in the interest of classic cars has caused a flourishing aftermarket industry and this includes classic lubricants. It’s not marketing puff either; there are considerable advantages in using a specialist lube designed for your classic oldie because there is no benefit in using an oil that’s ‘too good’ for your engine. It’s all down to the unit’s original design and the oil that was blended for it initially. A ‘classic oil’ from the likes of Castrol, Duckhams, Halfords, Morris, Millers Oils, Penrite and now Comma offers the best of both worlds: that is current standards in quality but twinned with traditionally refined formulations for the eras these oils were intended for. Now some of you will have cottoned on to two facts: 1) classic oils are expensive brews, and 2) you see budget 20W/50s around for a lot, lot less. Sure, dedicated classic oils are premium priced and you can certainly purchase five-litres of 20W/50 for around a fiver still, but these cheap oils won’t be anything like the quality your classic deserves (although they may be okay for a budget oil burning oldie drinking the stuff to be fair). If you want quality oil on the cheap seek out supermarket brands such as Tesco and Asda, or hypermarkets such as Macro, etc. Apart from normal oils you can also choose special lubes for fast road or motorsport use (some which are even synthetic-based). Also you can specify brews to help run an engine in after a rebuild or if it is to lay idle for long periods. Running-in oils are generally of low quality lacking the traditional anti-wear agents to encourage a speedy bedding down process. Conservation oils, such as Millers’ Classic Preservation Oil, contain a vapour that coats the internals and safeguards the unit against storage damage.

Playing it straight

On many older cars, such as pre-war, it’s wise to use a monograde over a multigrade (the latter an oil with two working grades; so for example a 20W-50 functions as SAE20 in cold winter temperatures and as an SAE50 in warmer summer months). SAE 30 is the most common, although a thicker SAE 40 is recommended for summer use. Multigrade oils were designed to alleviate the bind of using summer and winter oils and a 20W-50 lube is an equivalent of a mono SAE 30 albeit for all year use. If you are in doubt, speak to a specialist or your car club for advice on best oil to use as some cars, such as models from the 1950s and 60s, can still happily run a monograde lubricant. Don’t assume that the thicker the oil the beefier it is in service; it depends upon what engine it is being used in and some modern units are extremely oil sensitive. That said, a fuller-bodied oil in an aging, wearing unit can help control poor oil consumption, such as specialist classic 20W/60 blend (from Penrite), although most units in good order can cheerfully use a lighter 15W/40 quite safely, too.

Is a syn so bad?

Ah yes, synthetic oils. Because they are manmade, synthetics offer many advantages over a mineral oil, such as better protection, broader viscosity bands and a longer service life. That said, unless you own a modern performance classic such as a Sierra Cosworth or something turbocharged, synthetics aren’t too critical. In fact, their lighter constituency can lead to excessive oil consumption and even leaks, via worn seals and gaskets. Some experts also reckon a synthetic’s ‘searching’ characteristics disturbs sludge and debris lying in an old engine as well. If you wish to switch over to a synthetic, flush out the engine first at the very least to be safe.

What exactly does engine oil do?

Engines may have evolved, but the role of their lubricant hasn’t. Oil provides that indispensable protective shield between the engine’s sliding surfaces which look and feel silky smooth, but under a microscope are as jagged as the lunar surface. Without a film of oil an engine will seize up in seconds. But oil has to do much more than protect. It cleans the engine of harmful by-products of the combustion cycle such as acids, coke, tarnish deposits and so on and must do so for thousands of miles under all extremes of driving conditions, temperatures and engine revs. These days some synthetic oils can run for up to 20,000 miles without needing changing - but would you want to leave oil in a classic that long? Of course not!

What oil is right for your classic?


Essentially for vintage and veteran engines, especially those featuring roller bearing crankshafts. Some pre-1940 engines can’t use oils containing detergents so check first

20W/50 (20W/60)

Still a popular choice for classics although aim for SF level quality or a specialist brand. Specialist oils that boast a fuller bodied “60” rating are worth using to retain oil pressure

10W/40 (Semi synthetic)

Ideal candidate for modern fuel-injected, catalysed multi-valvers and hot GTis. A similar, cheaper top grade mineral is more suitable for most cars produced during the ‘80s


Generally a semi-synthetic, this is the right stuff for 70/80s engine designs. Huge choice, but ignore the fancy name and concentrate on the specs on the pack for top value

  • Oil’s well if you follow these tips
  • Change the oil frequently. There’s nothing worse than cold, acid-filled oil laying in the sump - as can happen to many low-use classics. Once a year change is the minimum
  • Don’t go for the cheap stuff. Sure it may have old era grading, but the quality will also be out of date. It’s only worth is on old smoking, oil-drinking engines where it’s a waste otherwise
  • Although everybody has their favourite brew, most quality oils are all much the same these days and it’s the specs on the pack which really count the most. So check them out
  • A flush is a good idea to remove all the gum - better still if possible, remove the sump and oil pan strainer and wash out the grunge even an oil flush cannot shift
  • You can experiment with lube grades; a slightly thicker oil can work wonders a wearing engine to improve pressure and oil consumption: say a 20W/50 or 20W/60 formulation
  • On the other hand, be careful on modern engines such as the Ford Zetec, which is very oil sensitive and needs a very light grade lube. Too thick and the engine will run poorly
  • Oil additives are a matter of choice and the debate rages on their worth. But it’s wiser to buy a quality oil than a cheapie plus then an oil booster to make it a good enough brew
  • Don’t use a racing brews such as good old Castrol R as road use turns this vegetable-based oil into a jelly-like goo which blocks up the oil ways. It’s for full throttle race tracks only!
  • Classic transmission oils and greases are also available and are well worth using as some older components are not suited to modern lubes or oil additives. Seek advice if unsure
  • Be warned, a lot of professional mechanics know little about this increasingly specialised subject, so use the helplines many oil producers operate to assist enthusiasts like us!

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