"What meets the requirements of the latest engines and gearboxes can't be wrong for a classic or vintage car!" Yes, it can! But let's start from the beginning:
What are the basic oil categories?
At the very bottom of the list is the distinction between unalloyed and alloyed oils.
"Unalloyed"
Unalloyed oils are, figuratively speaking, "natural" oils (exclusively mineral) to which no additives have been added. They lubricate, but have neither a cleaning effect nor do they actively keep dirt particles in suspension - and by definition they are always monograde oils (with very few exceptions, which we will discuss later). They are still used today, especially in pre-war vehicles without oil filters, because the lack of filtration means that it is undesirable for wear protection reasons alone that dirt circulating in the oil circuit (which always occurs) is kept in suspension or even additional deposits are loosened. Most of the circulating particles in unalloyed oil settle in the oil pan - shorter oil change intervals are advisable when using these oils.
Another property makes them irreplaceable for many pre-war vehicles even today: their compatibility with non-ferrous and white metals, which can be found in many bearings. Many additives have a detrimental effect on such bearings, which is why only unalloyed or guaranteed compatible alloyed oils should be used.
How do I recognize unalloyed oils?
Quite simply: the packaging/can should say "unalloyed" or "unalloyed" - the addition "HD" (Heavy Duty, higher load-bearing capacity due to EP additives) alone means that you are dealing with an alloyed oil.
"Alloyed"
All oils to which additives have been added. By adding chemically active components, the properties of the base oil are adapted and its capabilities enhanced - this is referred to as "formulation". The most common components are EP ("extreme pressure") additives, detergents (dirt-dissolving additives), dispersants (dirt-carrying additives) as well as anti-ageing agents, anti-foaming agents, antioxidants and friction reducers.
With all these additives, however, it would still be a monograde oil, which leads us to the 2 main categories of alloyed oils:
>> Monograde oils:
These are oils whose viscosity (viscosity) changes "naturally" over temperature - at higher temperatures it decreases, the oil becomes thinner and can therefore absorb less pressure and shear forces.
How do I recognize monograde oils?
Only one viscosity index is specified, e.g. "SAE 30".
>> Multigrade oils:
These oils contain polymers that "swell" at higher temperatures and thicken the oil. They therefore behave in exactly the opposite way to monograde oils depending on the temperature - and thus compensate for the naturally decreasing viscosity at high temperatures due to the polymer-induced thickening.
How do I recognize multigrade oils?
Well, these have the most common designations with 2 viscosity codes, e.g. "SAE 15W/40", whereby the first code indicates the viscosity of the base oil and thus the viscosity in the cold state and the second the viscosity achieved by polymer "swelling" at high temperatures. The "W" after the base viscosity comes from "Winter".
Special gasoline/diesel oil?
Diesel engines bring higher pressures to the main bearings due to the high compression - and in contrast to gasoline engines, they record soot ingress into the engine oil. Despite this, no special oil is necessary or advisable for diesel oldtimers and youngtimers. All petrol oils from "HD" upwards are more than sufficient in terms of load capacity, even for diesel engines with high power density. And the introduction of soot is not a problem at all in older vehicles, but even has a slightly positive influence on wear, because the soot behaves similarly to a solid anti-wear additive and reduces friction. In diesel engines, however, the change cycle should not be extended too much, because on the other hand, the soot ingress also ensures a certain chemical aggressiveness of the oil.
Special diesel engine oils are therefore only relevant for vehicles with particulate filters and modern emission standards, where the main concern is the sulphated ash content (low/mid SAPS). All diesel young & oldtimers can be driven with petrol engine oils without any problems. Nevertheless, we have a special diesel multigrade oil in our range that neutralizes the soot content somewhat and is perfectly suitable for most diesel vehicles from the 70s and 90s.
And what about "mineral", "semi-synthetic" and "fully synthetic"?
This is the differentiation according to the refining/production method of the base oil. Rol oil is broken down by atmospheric distillation into its two main components, crude petroleum and residue - now let's move on to our oils:
Mineral oil:
The residues serve as the basis - vacuum distillation and processing create the mineral oil. The refining process is therefore purely physical/mechanical. Mineral oils can be found in all the categories listed above, and the "unalloyed" category is theirs alone.
What are the advantages of mineral oil?
It is chemically "inert", i.e. it is very neutral towards sensitive metals and sealing materials.
Semi-synthetic oil:
The base oil is mixed together from mineral and fully synthetic oil.
Fully synthetic oil:
This term is colloquial and vague - because "fully synthetic" oils can be obtained from the residues as well as from the raw petrol and also still by different processes. The basic distinguishing feature compared to mineral oils is that their refining is partially or completely chemical. There are HC synthetic oils (based on residues), PAO and ester oils (based on crude petrol).
What are the advantages of "fully synthetic" oil?
It is both physically and chemically purer (e.g. greatly reduced sulphur content), more resistant to ageing and generally more efficient.
Now the confusion is complete and some people will think "it's obvious: I don't drive a pre-war classic car, fully synthetic oil is better in practically all respects, so I'll treat my classic to a PAO or ester oil!".
Stop! That's shooting sparrows with cannons and the negative side effects come at a cost. Because now there are all the additives in alloyed oils - and the API and ACEA specifications that control this and which in turn are largely dictated by (environmental) regulations and thus politics.
Why adapted young & classic car oil makes sense
All PAO and ester oils on the market comply with the latest API and ACEA standards... and these are only backwards compatible up to 1996. This means that the additives they contain can cause various undesirable effects and attack materials in vehicles older than around 1996 - starting with oil leaks, damaged seals and increased oil consumption due to combustion and, in unfavorable cases, ending with major engine damage. The question is not whether problems will occur, but when!
The classification of specifications SN and downwards as "obsolete" or "obsolete, can cause equipment harm" is (deliberately) misleading and made from the perspective of today's vehicle technology. The mere fact that current oils with these old specifications are significantly more efficient than contemporary oils of the time makes the warning classification absurd...
The arbitrary classification becomes clear when looking at the diesel API standards: here, older specifications are not supplemented with warnings, although diesel engines have made a much greater leap in terms of engine oil requirements. High-pressure direct injection systems and massive turbocharging have greatly increased the stresses on the oil.
This only affects the chemical composition, but there are also incompatibilities in the physical properties - specifically viscosity. Since the mid-1990s, production tolerances in engines have decreased significantly and fuel consumption and emissions regulations have been added, which have then been steadily tightened. In order to squeeze out the friction and thus the last bit of fuel consumption and exhaust gas optimization, the oils have subsequently become thinner and thinner. Too thin for classic and vintage cars, because in addition to the greater manufacturing tolerances, these engines are also subject to wear. In such a scenario, a current oil, e.g. SAE 5W/30, is too thin to build up a stable lubricating wedge. And the risk of oil leaks increases enormously, exacerbated by the chemically aggressive additives that attack the already not-so-fresh seals.
"...but there are also current oils with viscosities like in the past, e.g. 15W/40!"
Yes, but they also contain approx. 20% additives according to the latest standard and are not recommended for the reasons mentioned above.
Incidentally, owners of vintage or classic cars don't need to worry about the performance of the oil: a good mineral oil with the right viscosity (in summer it should be xxW/40) will only reach its limits in these vehicles in the toughest racing conditions (and our oils are of course all good ones!).
"Oh man, now I don't know what to do! Which oil should I put in my favorite?"
A special classic/youngtimer oil! Our classic oils are formulated for maximum compatibility with materials used in the past and are available in the right viscosity - and in some cases even cheaper than any DIY store oil according to current API and ACEA standards.
Here are a few rules of thumb:
Pre-war vehicles (ca 1900 to ca 1945):
If the engine has not been overhauled, an unalloyed oil according to the manufacturer's viscosity specification of the time is the first choice. In most cases, SAE 30 unalloyed is used. If it is already leaking somewhere and you only drive in the warm season anyway, you can also go one viscosity class higher to SAE 40.
If the engine has been overhauled and no white/non-ferrous metal bearings are installed, you can also fill it with alloyed HD (heavy duty) monograde oil. If no oil filter has been retrofitted, slightly more frequent oil changes are sufficient to keep wear to a minimum. So if the manufacturer prescribed SAE 30, SAE 30 HD would be an option.
Early post-war vehicles (ca 1940 to ca 1955):
If the engine has not been overhauled, an alloy HD monograde oil (usually SAE 30 or 40 HD) can usually be used, even if the vehicle does not have an oil filter. In this case, the oil should be changed a little more often (let's be honest, with most collector's cars the oil is changed more often than actually necessary anyway...).
If the engine has been overhauled and the oil filter retrofitted, these vehicles can already change to multigrade oil. In this case, the absolute standard is recommended, which is also used for the following decades: a mineral SAE 20W/50.
Vehicles from the 60s to 80s:
Apart from a few exceptional designs, a universal recommendation: the mineral SAE 20W/50 mentioned above! For vehicles from the 70s and 80s that are also used in winter, an old/youngtimer-compatible 15W/40 can also be used.
A note on the zinc content in the oil requested by many owners of American classic cars: Zinc used to be added as wear protection and can be found in many US manufacturer recommendations. The metal acts both mechanically and chemically, but has long since been superseded by developments. The formulation of today's classic car oils protects against wear much better than an oil with zinc content, even without zinc. Nevertheless, there are effective amounts of zinc in our classic car oils - but looking specifically for an oil with a particularly high zinc content is useless in every respect.
Vehicles from the late 80s to the late 90s:
This is where the gap widens - while many bread-and-butter engines are best served with the well-known mineral SAE 20W/50 or a mineral SAE 15W/40 for seasonal operation, a partially or fully synthetic high-performance oil such as our SAE 10W/60 Ester is very suitable for certain high-performance engines such as BMW's M engines.
Separate additives
Additives can raise even the best oils to an even higher level of performance and protection. Our Micro Ceramic, which can be used in any oil and outperforms even the best fully synthetic high-performance oils in terms of wear protection, performance reserves and mechanical smoothness, deserves special mention here.
The question often arises as to why we do not offer ready-mixed Micro Ceramic oil: this is a solid additive with particles, and with a ready-to-use mixture there would be a risk of too many effective components remaining in the canister if it were not mixed sufficiently when filling.
The solids-free alternative is called Classic Oil Additive, is based on an organic complex and comes close, but not quite, to the performance of Micro Ceramic. We also offer two ready-to-use engine oils: the semi-synthetic SAE 10W/40 Premium and the mineral SAE 20W/50 Premium.
A note on oil additives: no more than one should be added, as they are usually added to alloyed oils - and the tendency to foam increases from approx. 20% additivation. Our oils offer sufficient scope for the addition of an additive. As an exception, our Oil-Stop can be combined as a second oil additive with e.g. Micro Ceramic or Classic Oil Additive.
Here too, the use of oils for modern vehicles in classic and vintage cars is disadvantageous, as these are already highly alloyed (= maximum additive content) and leave little scope for useful and cost-saving additives such as Oil-Stop.
Conclusion: There is no reason for owners of classic and vintage cars - neither financially nor technically - to look enviously at oils for modern vehicles.
Special oils for older vehicles are the right choice!
Ultimately, the oil must suit your own vehicle and its history (condition of the engine). Our telephone support on 09085 - 96 00 90 offers competent help and individual recommendations - it is helpful if you make the request via our oil advice form, then we have all the vehicle data at hand for the conversation and can research in advance if there are any uncertainties.
