Your car’s engine oil plays a crucial part in your car’s functionality. Without oil, the engine wouldn’t be able to function properly. Engine oil is used to lubricate the different parts of an engine and in addition, is also used to manage the heat of the engine (thus, preventing it from overheating).

Over time your engine oil will begin to deteriorate and as a result, you must change your oil. If you choose not to check your car’s oil regularly and you don’t change it when needed, some serious (and expensive) damage may result. With this in mind, below is a list of common signs which indicate that you should change your engine’s oil.

Sign #1 – Why is my transmission or differential oil low?

Gear oils play a similar role to that of engine oil and provide protection for both the differential and manual transmission. Ultimately, gear oils allow both of these vital parts to do their jobs effectively. By having a low oil level, proper lubrication of all moving parts may not occur, this can result in damage occurring in these parts. Most modern automatic vehicles provide you with an easy way to check the level of your transmission oil, some however can be more difficult or “sealed” for the life of the vehicle.

For vehicles with a dipstick located under the bonnet this can be quite easy. First, make sure that your engine is warm after a short drive, put the vehicle in park (Take care in checking fluid levels with your engine running as your engine can be quite hot). Remove the dipstick, wipe off any excess oil with a rag, re-insert the dipstick, and remove it again. If the gear oil appears dark or gritty, then it should be changed. You can find what type of oil is recommend for your vehicle using our Parts Guide.

Some transmissions and differentials have filler plugs, this is used to check oil levels and top up, If you cannot check your oil level, book it in for an inspection with your local mechanic through our mechanic finder.

Sign #2 – Why is a sound coming from my gearbox/differential?

Differentials and gearboxes are made from many different gears which intertwine with one another. How effective gears and components work depend on how well those gears are arranged to interlock with each other as well as the quality of the oil to lubricate them. For example, if your gear oil is low or hasn’t been changed for a long time, the gears may not be lubricated sufficiently and then you hear a whining noise of the internal gears pushing against each other.

Any new noises coming from your car is something to be concerned about but fortunately, when it comes to your gearbox or differential, this whining noise could be resolved as simply replacing the gear oil. If you find the gearbox or differential sounds the same after an oil change, you may have damaged internal parts inside the component. This will need to be inspected by professional, use our mechanic finder to find one near you.

Sign #3 – Why is my gearbox making noise in neutral?

Noises from the transmission while in neutral signals an internal issue, such as mechanical wear that may need the replacement of various components. Common parts that are worn include bearings, synchromesh, cones, dog teeth and possibly coupled with worn gear teeth. Ensuring that your gearbox/differential oil is new and full will help lubrication of these parts. If parts need to be replaced, we recommend repairs are completed by your local professional.

Sign #4 – Why is my gearbox is slipping or not selecting gears?

If your car is slipping between gears or you feel as though the gears are jerky then this may indicate that there is something wrong somewhere in your transmission system; something which can be incredibly expensive to have repaired. Before jumping to conclusions, it’s always good to check gear oil levels.

Most modern vehicles provide you with an easy way to check the level of your gear oil, some however can be more difficult. For vehicles with a dipstick located under the bonnet this can be quite easy. First, make sure that your car is running and that it is in park (Take care in checking fluid levels with your engine running as your engine can be quite hot). Remove the dipstick, wipe off any excess oil with a rag, re-insert the dipstick, and remove it again. If the gear oil appears dark or gritty, then it must be changed. If the gear oil level is low, top it up.

If topping up the transmission oil doesn’t help with this, you may have internal components that have failed. We recommend booking an inspection with your local mechanic to find the issue.

Sign #5 – Why is there a burning smell from my gearbox/differential?

If your gearbox or differential smells as through its burning oil, you may have an oil leak which is weeping out of an old oil seal. Have a look at your driveway to see if there is any red oil or better yet, have a look underneath your vehicle for oil leaks. Gaskets and seals can be ordered using our Parts guide.

Another common cause of this smell is that the gearbox is getting too hot as a result of improper lubrication. If the oil is too old and cannot lubricate properly this in turn will cause the metal components to heat up excessively and burn oil. Replacing with new oil may help with this issue.

If gaskets or seals need to be replaced, we recommend repairs are completed by a professional, try our mechanic finder to find one close by.

Sign #6 – Why is my check engine light is on?

A check engine light is one of the main causes for concern for any driver, but you can use this light to find out if there’s something wrong with your car before any serious damage is caused. There are a lot of different reasons for the light to come and shouldn’t be ignored, one reason for the light to illuminate is low gear oil. Take advantage of this signal and have one of our friendly team members complete a diagnostic test. They will be able to provide a thorough test and find out if the cars computer registers an issue with your gear oil, or if something else is wrong.