Millers Oils

1. Are modern engine oils suitable for older vehicles?
No. Modern engines are designed to run on very low viscosity (thin) oils. 5w is common and 0w oils are starting to appear. These are much too thin for older engines, which were designed to run on 20w in the winter and 30 or 40 grades in summer.

2. Which oil should I use in my vintage car or bike engine?
Vintage, i.e. pre WW2 cars had very primitive oil filtration systems and used non-detergent oils, such as our Millerol range. The Millerol range contains anti-wear and anti-corrosion additives, but does not contain detergents. A lower viscosity oil would be needed in the winter, such as Millerol 30 and a higher viscosity in the summer, such as Millerol 40. The gearboxes also use the same type of oil, usually a higher viscosity than the engine, e.g. Millerol 50.
The oil needs to be changed regularly due to the lack of detergent content.

3. Is it possible to use a more modern type of oil in these very old engines?
Yes. Our later formulations, Pistoneeze and all our multigrades are detergent oils. Detergents keep the oil clean by holding the products of combustion in suspension in the oil and prevent the formation of sludge in the sump. It is possible to use these types of oil (of the correct viscosity) providing you are sure that the engine is clean inside and does not have any build up of sludge. This will be the case if it has been freshly rebuilt or is already running on a detergent oil.

4. Which engines would use your Classic 20w50?
Classic 20w50 is a mineral multigrade and is typical of the viscosity of oil specified for the majority of engines from 1960 to 1980. As mentioned above, it can be used in older engines providing they are clean inside. Being a multigrade, there is no necessity to change the oil between winter and summer.

5. Why do you also sell Classic Sport 20w50?
Classic Sport 20w50 is a semi synthetic version of Classic 20w50. Being a semi synthetic, it has a higher performance capability than Classic 20w50. It has been developed for high performance classics such as Jaguar, Aston Martin, MG, Triumph, Porsche, Alfa Romeo etc. It is perfect for tuned engines and /or high speed running.

6. Did I hear that you do special oil for the original Mini and other applications where the engine and gearbox share the same oil?
Yes, Classic Transverse M 20w50. Again it is a version of Classic 20w50, but it contains additives that protect the gearbox. It is also perfect for gearboxes that specify a 20w50 engine oil (e.g. MG and motorcycles), as it will give additional protection to the gears and the overdrive.

7. Do you have a 2-stroke oil suitable for older 2-stroke engines?
Yes. Traditionally, the most popular 2-stroke oil was an SAE 40 mineral oil. However modern 2-strokes require a low smoke, semi synthetic 2-stroke oil with a much lower viscosity, SAE 15. Older 2-strokes, do not appreciate these thinner oils, so we produce CM2T which is a mineral SAE 40. We also dye it blue, so that you can tell if you have treated your fuel.

8. I have just rebuilt my engine, how do I run it in?
Millers make a special Classic Running In Oil, which should be used for the first 500 miles. After this, you should change the oil filter and replace the running in oil with the engine oil of your choice.

9. Do you have any other specialist products that we should be aware of?
Yes, we have Classic Preservation Oil, which is based on Classic 20w50 and contains a volatile element that condenses on all the surfaces in the engine and prevents corrosion during storage. As it is based on Classic 20w50, it is also suitable for occasional use, although the volatile elements will eventually evaporate away and reduce its preservation capability.
We also have a special oil for steering boxes. It is far superior to standard gear oil as it contains friction modifiers, which reduce the friction between the gear and the pinion resulting in better steering feel. Worm Steering Box Oil is used and recommended by the Rolls Royce Enthusiasts Club.

10 The various different types of gear oil confuse me. What does GL1, GL4, and GL5 etc. mean?
There are 4 levels of performance in classic gear oils and these really follow the development of gear design.

GL1 is the lowest level of performance and is only used in vintage transmissions. It is very similar to engine oil, having a very low additive content, but is available in much higher (thicker) viscosities to suit gearboxes with unsophisticated oil seals. Millers Green Gear Oil range of GL 1 oils goes up to SAE 250 viscosity.

GL3 is the next level of performance and has very limited applications. Mainly specified for French and Italian (Fiat & Alfa) cars which had very soft synchromesh. It has very low EP (extreme pressure) performance and does not contain the concentration additives used in later formulations.

GL4 is the first serious level of EP performance and is specified for many gearboxes and final drives from mid 1930’s onwards.

GL5 specification is for highly loaded hypoid differentials as fitted to most cars from 1960 onwards.

11. Which gear oils do I use in my vintage car that has lots of yellow metal in the gearbox and differential?
A GL1 oil will be the closest to the original specification and is available in the heavier viscosities.

12. What is your Classic Sport Transmission Oil 80w90?
This is a high performance semi synthetic GL4/GL5 gear oil. All our other Classic gear oils are mineral oils. It is suitable for high performance and tuned classics, or wherever the user wants a superior product to a mineral gear oil.
As it is both GL4 and GL5 it can be used in both gearboxes and differentials.