Confidence Comes from Within

Different types of gearboxes require different oils

Not using the right product can cause serious performance issues and even render the vehicle undriveable as different gearbox technologies have different lubrication requirements. CVTs (Continuously Variable Transmissions) and DCTs (Dual-clutch transmissions) are becoming more common in the vehicle parc (approximately 9% in total) and present some challenging requirements when it comes to gearbox oils, as well as interesting servicing opportunities.

CVT (Continuously Variable Transmissions)screen-shot-2016-12-01-at-09-02-19

In a CVT, conventional gears are replaced by two variable size drums and a drive belt or chain. The belt or chain runs in a groove formed between the sides of each drum. The diameter of each drum is controlled by the transmission computer through the action of hydraulic cylinders, applying or reducing oil pressure to the movable part of each drum. When one pulley increases its radius, the other decreases its radius to keep the belt tight. As the two pulleys change their radius relative to one another, they create an in nite number of gear ratios, from low to high and everything in between. Thus, in theory, a CVT has an in nite number of “gears” that it can run through at any time, at any engine or vehicle speed. The efficiency and durability of the pulley system used in CVTs depends on the system’s friction performance. Also, some of these transmission systems do not use a conventional clutch but instead use a torque converter, just like the conventional automatic gearbox.

CVT transmissions account for approximately 6% of the UK vehicle parc with the average sump size being 5.5 litres (this is compared to an average of 3 litres for manual transmissions and 6 litres for a conventional automatic). The CVT fluid must be changed according to the manufacturer’s recommended service interval and anytime it is found to be faulty (periodic checks should be performed to make sure that the CVT is kept in good working order).

DCT (Dual Clutch Transmissions)

A dual-clutch transmission, or a DCT, is a type of semi-automatic automotive transmission. It uses two separate clutches for odd and even gear sets. It can fundamentally be described as two separate manual transmissions (with their respective clutches) contained within one housing, and working as one unit.

There are two fundamental types of clutches utilised in dual-clutch transmissions: either two wet multi-plate clutches which are bathed in oil, or two dry single-plate clutches. In terms of lubrication, the “dry” conventional type requires conventional manual gearbox oil, however, the “wet” type has some extra requirements for oil so that the oil does not in influence the friction characteristics of the clutch which can cause the clutch to slip and ultimately, to not work at all.

DCT transmissions account for approximately 3% of the UK vehicle parc and the average sump size is of 6.4 litres (the manual transmission average is 3 litres with the conventional automatic average being 6 litres). The DCT uid must be changed according to the manufacturer’s recommended service interval and anytime it is found to be faulty (periodical checks should be performed), to make sure that the DCT is kept in good working order.

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What happens if I don’t use the right product?

Not using the right product can cause serious performance issues and even render the vehicle undriveable as different gearboxes have different lubrication requirements. Remember, gear oils come with industry/manufacturer’s specifications and not using a product that meets the requirements can void warranties.

How to get it right?

To make this increasingly complicated choice a lot easier, you can use the VRN lookup facility or make and model function at www.CommaOil.com. You will then be presented with a printable full vehicle product report including engine oil, antifreeze & coolant, transmission oils, brake fluid and greases, if applicable.

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