Inside Line: Comma


A few notes about the Jaguar XJ (X350/X358 series):

Engine Oil

Jaguar generally favour a product like Comma Xtech 5W30 for most of their applications however there are some exceptions, particularly in the older models in this series.

Supplying the customer with a top up pack and reminding them that they should be checking the engine oil regularly (check handbook for guidance) might also be prudent here particularly if you have noticed that the oil needed topping up when it was brought in. A quick check before you change might be a good way of reinforcing the importance of top up to the customer. Combined with longer service intervals and the increased use of sensitive components like turbochargers, checking your oil is more critical than ever before.

Brake Fluid

Mostly conventional DOT 4 brake fluid however newer models do specify a low viscosity product like Comma DOT 4 ESP so please use our application guide which can be found at to make sure you get the right product.

Most people don’t think of brake fluid as a service item however, as with many manufacturers, Jaguar specify a change interval of 24 months for this series of XJ. Brake fluid degrades over time by absorbing water from the atmosphere (even when it is apparently sealed inside the system) which lowers its boiling point. Boiling point is a critical factor in brake fluid performance because of the amount of heat generated during braking. If the boiling point of the fluid is too low then continuous or hard braking may cause the brake fluid to vapourise which in turn can result in a loss of hydraulic pressure within the system (ie your brakes don’t work when you most need them too). The message here is that brake fluid is a safety critical item so check and change when specified – don’t assume that it will just be OK.

Power Steering Fluid
This particular range of Jaguars is fitted with power steering systems with varying requirements across the production cycle.


Xstream G30 is the recommended product for this XJ series, as it is for most Jaguar vehicles from 1999 on.


For this particular series of XJ, Jaguar uses a range of transmissions that includes manual but almost usually automatic transmissions and various specifications. As well as the different fluid requirements, change intervals and capacities will vary depending on the type and year of transmission so we would advise you to consult the handbook to ensure that you get the right product for the vehicle you are servicing.

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