Millers Oils

1. Are your Motorsport engine oils different to your road car oils and why?
Yes. Millers Motorsport engine oils have completely different formulations to our normal road oils. Road oil formulations must comply with the vehicle manufacturers’ specifications, which are increasingly driven by factors such as fuel economy and lower emissions. Millers Motorsport oils make no such compromises and are formulated for maximum performance under the most arduous conditions.

2. OK, so what exactly are the differences?
Firstly, Millers Motorsport oils use the highest quality synthetic base oils and additives.
All Motorsport oils are multigrades, and you will recall that additives called polymers are added to make the base oils into a multigrade. The problem with polymers is that they “give up” in areas of high shear, e.g. in the crankshaft journals and between the camshaft and the cam follower. In other words, they become thinner in exactly the areas where they should not.
Millers Motorsport oils use additives called esters to replace the polymer and therefore improve the “strength” of the oil in areas of high shear. More detailed information on esters is available in the article from Race Engine Technology magazine in the motor sport downloads section.

3. Does it follow that the best oil will be 100% ester?
No. The best performance is obtained from a blend of esters and full synthetic base oils. This is why Millers use a blend of 3 different esters with full synthetic base oils and other sophisticated additives in their Motorsport range.

4. I notice you have some semi synthetic oils in the Motorsport range. Why is this?
Certain types of engine will perform very well on semi synthetic oil even in Motorsport applications. These are mainly engines from the 50’s and 60’s such as MG, Austin Healey, Jaguar and race engines developed from the Ford Kent and Pinto engines. These were designed to run on a 20w50 and Millers semi synthetic CSS 20w50 is ideally suited to these applications. We also make COR 20w50, developed primarily for short circuit and oval racing. These oils are ideal for these applications and are less expensive than our full synthetic Motorsport oils.

5. Do I need a special running in oil for a motorsport engine?
We would recommend this, definitely. It is very difficult to get new piston rings and bores to run in on a full or semi synthetic oil. Millers therefore produce a competition running in oil CRO 10w40. This is a very high quality mineral oil which will protect the cams, followers etc. whilst still allowing the rings to bed in. It can be used for the running in process on both a dyno or on the road. You can download a running in procedure from the Motorsport downloads section of www.millersoils.co.uk.

6. You seem to produce a lot of different viscosities, how do I decide which viscosity to use for my engine?
It depends on the state of tune. Start with the recommendation in the owner’s handbook. If it suggests 5w40 for standard road use and this is your intended use, you should go for CFS 5w40.
If the engine will be driven hard e.g. occasional track days, you can upgrade to CFS 10w40. If it is very highly tuned, raced, rallied, frequent track days etc, it is wise to upgrade to CFS 10w60. You can apply this principle to all applications.

7. What is the difference between an engine oil and a gear oil?
In the early days of motoring, the same oil was used in engines and transmissions. Today, they are very different. All Millers Motorsport gear oils are GL4/GL5, either semi or full synthetic and can be used in all gearboxes and non-limited slip differentials.

8. What type of oil should I use in a limited slip diff?
It depends on the type of LSD. The “plate” or “Salisbury” type of LSD uses small clutch plates each side of the differential. These need a special limited slip oil, which contains friction modifiers to reduce squeal and provide smooth power take up. Suitable Millers gear oils have LS in their name. The cam and pawl and torque-biasing differentials do not need an LS oil, just a very good performance gear oil, although there is no harm to be done in running these types on LS oil.

9. Are there any exceptions to this guideline?
Yes. Unfortunately synchromesh does not like friction modifiers. They make it slip when it is trying to grip, and could cause the gear change to become difficult. Hence a problem arises in some front wheel drive cars where the synchro gearbox shares the same oil as a plate type LSD. Millers CRX 75w90 full synthetic competition gear oil is the best compromise, as it has been formulated with this situation in mind.

10 Why do you sell heavy-duty gear oils, i.e. the 80w140 viscosity?
In some applications the gears are not physically large enough to transmit the power and torque. In theses circumstances the hardening on the gear tooth can break down and rapid wear will result. A heavier (higher viscosity) oil will cushion the gears and enable them to transmit more power/torque without wearing.

11. What is meant by BM on the names of your gear oils?
Millers range of BM oils have additional semi solid additives that react with and coat, the surface finish of the gear teeth to cushion shock loads, reduce friction and improve gear life. They also help protect the sharp edges on gear and dog rings in dog-engaged gearboxes. As these oils also contain limited slip diff additives, they should not be used in synchromesh gearboxes. There is a BM version in each range of viscosities.

12. 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.

13. 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.

14. 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.

15 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.

16. 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.

17. What should I use in a racing engine?
Millers CVL (competition valve lubricant) is specially developed to enable older engines used in motor sport to run on unleaded fuel. It is formulated to comply with the FIA fuel regulations.

18. 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.

19 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.