How regularly should the coolant be changed?

Hi Paul, I have owned my 2004 Nissan X-Trail for three years now since I bought it from Japan. It has been running well. I would like to know how often I should service my engine coolant. Recently I noted that my service bay mechanic has not changed the coolant fluid since I got this car. When I asked him why we were not servicing the coolant, he replied that the coolant colour was still red so it did not need to be changed. Joshua.

Hello Joshua, engine coolant service should be carried out every two years. This means draining all the fluid in the system and renewing it with a suitable coolant fluid.
Coolant fluid is critical because it has three major elements in its composition. An anti-corrosive agent to prevent rust and corrosion damage of cooling system components. Coolant also has a lubricant glycol which ensures smooth running of moving coolant system components like the water pump as well as a heat depressant agent to reduce engine heat.
These chemical agents will deteriorate over time as they are heated and cooled. The colour of coolant can be deceptive yet its efficacy has reduced.
In fact, overdue coolant will become corrosive and start to damage the cooling system components hence the two-year service interval.
It is recommended that you buy coolant suitable for your car and the Ugandan climate. The coolant dealer will explain to you or your mechanic how it works and the drain interval.
I suggest you find a knowledgeable technician to service the cooling system and avoid causing an overheating episode.

Hi Paul, Thanks again for the work you do to make car owners get knowladge on the safety and operation of these machines as well as service.
My question is: What makes a car vibrate at high speed when ever I reach high speeds of 120 kph?
I feel vibrations on the steering wheel and when I reduce the speed, these vibrations also reduce or disappear. What could be the problem with my car? It is a first generation RAV4. Mbabazi

Hello Mr. Mbabazi, vibration, juddering or extreme feedback at different speeds as you drive will suggest one of a couple of issues to do with the wheels or suspension of your car.
It would be a good move to start with an inspection of your wheel alignment. If that is done or corrected carry out a test drive.
Should the problem persists, examine your tyre treads and side walls. Unevenly worn-out tyre treads or bulging side walls will cause your wheel not to move unilaterally.
This results in a vibrating sensation as you pick up the pace when driving. Another area to investigate is the condition of your front RAV4’s wheel hub bearings and lateral suspension arm bushings.
If any of these two are worn out or damaged they will prevent unilateral movement of the wheels and cause a wheel kidder or vibration. This condition should not be ignored as your wheels could fall off in extreme situations.

Hi Paul, I drive a VW Golf MKIV 2002 model. I recently bought it from Japan with 120,000 kms on the clock.
The engine sounds fine but the automatic gearbox delays to shift especially when driving up a hill. A mechanic I know suggests that I buy a new gearbox. What can I do? Benjamin.

Hello Benjamin, with automatic transmission systems poor shift quality can be caused by electrical or mechanical breakdown. However, in most cases, it starts with a failure to maintain the hydraulic condition (Automatic Transmission Fluid or ATF).
Start by servicing or renewing the VW Golf ATF with a suitable fully synthetic Dexron iii product.
Automatic gearboxes rely on ATF to build viscous or fluid pressure which helps to engage gears. The same fluid helps to lubricate as well as cool down the very hot components of the gearbox.
ATF also carries away carbon deposits to the filter as it travels to the gearbox cooling system. It is useful to carry out an automatic gearbox service at 100,000 kms or when you find the ATF with a dark brown colour regardless of mileage.
A change of colour means that the ATF is not only dirty but has reduced ability to carry out its protective and performance enhancing role in the gearbox.
When renewing the ATF you should also replace the automatic gearbox filter and pan gasket (see picture). The gearbox filter is critical for trapping deposits and cleaning the oil as it travels around the gearbox.
When the filter ages, its functionality ceases and allows deposits to travel back and damage the solenoid valves in the hydraulic valve body, a sort of logistical hub which helps to actuate gears by releasing ATF to the selected gear.
Should the poor performance of the gearbox persist after your mechanic carries out the above service action, then find a diagnostic garage to run a computer diagnosis.
This should promptly reveal if your gearbox has mechanical or electrical damage.

Ask the mechanic: 0772316145, send sms: mycar (space) your comments and questions to 6933, or email them to [email protected]