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ENGINE OILS
1. What does the “viscosity” of an oil mean?
Viscosity is a measure of the thickness of an oil. The viscosity (thickness) of the oil at low and high temperatures is measured on a scale determined by the Society of Automotive Engineers and given a number known as the SAE number.
Therefore SAE 30 oil will be thinner than an SAE 40.
2. What is meant by multigrade?
Multigrade oils were developed in the 1960’s and have a designation in the format 20w50. Prior to this, all oils were monogrades.
This was made possible by the invention of polymers. Polymers are clever molecules that expand as they get hotter. Therefore a multigrade oil can have the viscosity of an SAE20 when it is cold and the viscosity of an SAE50 when hot. This removes the necessity to change from a thin oil in the winter to a thicker oil in the summer.
The 20w number is the cold viscosity and the 50 number is the viscosity at 100 centigrade.
3. What is the difference between a mineral and synthetic oil?
Both types begin with crude oil. Mineral oil is obtained directly from the refining process, whereas synthetic oils are subjected to chemical processing which alters and improves its chemical structure. Synthetic oils therefore have better performance than mineral oils at higher and lower temperatures, but are inherently more expensive.
4. What are the specific characteristics and advantages of synthetic oils?
As with mineral oils, there are differing levels of quality within the definition of synthetic oils, but the general advantages are:
• Better flow at low temperatures enabling thinner oils to be manufactured. Thinner oils are required by modern engine designers to help reduce fuel consumption and emissions.
• Higher film strength thereby reducing wear.
• More stable and less volatile at high temperatures, reducing oil consumption
(Note; for a detailed explanation, refer to the article from Race Engine Technology magazine in the Motorsport downloads section).
5. What is a semi synthetic oil?
As the name suggests, a semi synthetic is a blend of mineral and synthetic base oils. The performance (and price) therefore falls roughly mid-way between a mineral and a full synthetic oil.
6. Do I need different oil for a diesel and petrol engine?
Generally the answer is yes for older vehicles, as diesel engine oils have higher detergency levels. It is important to refer to the vehicle manufacturers handbook to establish exactly which specification of oil is required. This is vital if your car has extended service intervals and you are still within the warranty period.
However the latest trend on new vehicles is to use the same formulation on petrol and diesel versions.
7. Why are synthetic oils more expensive than mineral oils?
It is all about quality and performance. A synthetic oil is subjected to much more sophisticated manufacturing techniques and this means it is more expensive to manufacture. However, it has many performance advantages (see Q4) which justify the additional cost. For example, it enables longer service intervals, reduces oil consumption and contributes to improved fuel consumption. It follows that a semi synthetic oil will cost more than a mineral, but less than a full synthetic.
PETROL ADDITIVES
8. Under what circumstances should I consider using a fuel additive?
You need to consider using a petrol additive if you have an older vehicle that was designed to run on leaded fuel or in any vehicle where you wish to improve it’s performance or fuel efficiency.
9. What does a petrol additive do?
Millers petrol additives increase the octane of the base fuel, prevent detonation and allow older engines to run safely on unleaded fuel.
10. What is meant by the octane number?
The octane number is a measure of a fuels ability to resist detonation. The higher the octane number, the more resistance a fuel will have to detonation. This enables the engine to be more highly tuned and to release more power and / or improve the fuel consumption. The higher the octane number, the better the fuel.
11 Do Millers produce a lead replacement additive?
Yes, Millers VSP Plus. In the past, Tetra Ethyl Lead was introduced into petrol to improve engine performance by adding octane. It also lubricates the valves and prevents valve seat recession. Millers VSP Plus uses a compound of manganese known as MMT to replicate the benefits of lead.
When added to unleaded petrol, it will add 2 octane numbers, prevent the onset of detonation and lubricate the valves. 97 unleaded becomes the equivalent of 99 leaded.
12. Are all lead replacement additives the same?
No, The majority are only valve lubricants and do not add any octane. Millers VSP Plus is different as it adds octane as well as providing valve lubrication.
13. Which additive should I use to get maximum performance from my car?
Millers CVL Turbo will add 4 octane to the base fuel. This means that up to 103 octane is available by using Shell V Power or a similar premium unleaded fuel. This combination is ideal for Motorsport or track day use in all performance engines.
14 Is it OK to use CVL Turbo in a car fitted with a catalytic converter?
Yes, no problem for track day and occasional road use, but is not recommended for continuous use. We have a product called Octane Plus (which adds up to 2 octane numbers) which is suitable for continuous use in vehicles fitted with a catalyst.
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