Inside Line: Comma


Engine Oil

For this particularly 3 series, BMW list only one or two specifications for engine oil which should be covered by Comma Longlife 5W30 or Syner Z 5W30 for the later cars. However, always use Comma’s application guide available at to make sure you get the right product for the vehicle you are servicing.

Some of the engines in this 3 series have quite small sumps – the 320i for example has a 4.25L capacity. With service intervals varying according to the use of the car, oil top up between services can be critical. Supplying the customer with a top up pack and reminding them that they should be checking the engine oil regularly (see 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, a smaller sump size makes checking your oil more critical than ever before.

Brake Fluid

BMW use one or two specifications for brake fluid for this era of 3-series. Most people don’t think of brake fluid as a service item however, as with many manufacturers, BMW specify a change interval of 24 months for this 3 series. 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 vaporise which in turn can result in a loss of hydraulic pressure within the system (i.e. your brakes don’t work when you most need them to). 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

BMW use one or two specifications for power steering fluid for this 3 series and you can rely on Comma’s online application guide available at to identify which product is suitable for the vehicle you are servicing.


Xstream G48 is the recommended product for this 3 series, as it is for all recent BMW vehicles.


For this particular 3 series, BMW uses a range of transmissions that includes mostly manuals but also some automatic alternatives. As well as different fluid requirements, change intervals and capacities will vary depending on the type of transmission so we would advise you to consult the handbook.

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