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1. What is the function of Engine Oil?
2. How often should I change my Engine Oil?
3. How do I know when my car really needs a brake job?
4. How can I tell when my tyres need changing?
5. How often do I really need to have my wheels aligned?
6. How to read tyre sidewall?
7. How much air should I put in my tires?
8. Is it still necessary to rotate the tires every so often?

 

What is the function of Engine Oil?

The principal function of the engine oil lubricant is to extend the life of automotive that operates under different conditions like speed, temperature and pressure.

Sufficient lubricant in automotives reduces friction and removes heat from the engine. At low temperature to maintain the performance of the engine, where at higher temperature to keep the engine apart to minimize engine wear. Regular oil changes have a variety of benefits: they should give your vehicle a longer life, make you engine run smoother, improve your MPG and reduce emissions. So, in the long run this should mean more money in your pocket as your car's day to day functioning is improved and its life time is extended. It may not affect your car insurance rates, but it should cut the cost of servicing and maintenance. So, just by using sufficient engine oil you should make your car healthier and happier.


How often should I change my Engine Oil?

Most vehicle manufacturers recommend changing the oil once a year or every 5,000 miles in passenger car and light truck gasoline engines. For diesel engines and turbocharged gasoline engines, the usual recommendation is every 3,000 miles or six months.

A new engine with little or no wear can probably get by on 5,000 mile oil changes. But as an engine accumulates miles, blow by increases. This dumps more unburned fuel into the crankcase which dilutes the oil. This causes the oil to break down. So if the oil isn't changed often enough, you can end up with accelerated wear and all the engine problems that come with it (loss of performance and fuel economy, and increased emissions and oil consumption).


How do I know when my car really needs a brake job?

You need a "brake job" when your brake linings are worn down to the minimum acceptable thickness specified by the vehicle manufacturer or the applicable state agency in areas that set their own requirements. The only way to determine if new linings are required, therefore, is to inspect the brakes.

You may also need a brake job if you're having brake problems such as grabbing, pulling, low or soft pedal, pedal vibration, noise, etc., or if some component in your brake system has failed.

There is no specific mileage interval at which the brakes need to be relined because brake wear varies depending on how the vehicle is driven, the braking habits of the driver, the weight of the vehicle, the design of the brake system and a dozen other variables. A set of brake linings that last 70,000 miles or more on a car driven mostly on the highway may last only 30,000 or 40,000 miles on the same vehicle that is driven mostly in stop-and-go city traffic.


How can I tell when my tyres need changing?

One sign that your tyres need changing is noticing a deterioration in performance. For example, your car does not handle or grip the road as well in poor weather conditions as it normally does, or it takes longer to stop when you apply the brakes.

You should also be aware that there are many different reasons for tyre wear. Your tyres don't just get worn through age and use, but through emergency braking, under-inflation or over-inflation. And if your wheels are misaligned, one edge of the tyre can wear more rapidly than the other edge.

We recommend a weekly walk around the car to check the tread, look for bulges or wear and to check tyre pressures everytime you fill the tank.


Illustrations and explanation for tyre wear

  Under Inflation

Under-inflation has caused this tyre to wear on the outer edges of the tread, leaving the central tread area far less worn. The tyre inner-liner can also degrade.
     
  Over Inflation

Over-inflation has resulted in the central tread area being forced into contact with the road causing rapid or crown wear.
     
  Mis-Alignment

A typical example of the wear pattern caused by front wheel misalignment, (Toe-in or toe-out). The edge of the tread is "feathered" and worn progressively from one side.
     
  Camber Wear

Excessive wheel camber has caused sloping wear on the outer edge of the tread on one shoulder of this tyre.
     
  Illegal Wear

This tyre has been used well after reaching the legal minimum pattern depth of 1.6mm across the central ¾ of the tread, going around the complete circumference of the tyre.
     
  End Of Life

This tyre has reached the legal minimum pattern depth of 1.6mm.
     
  Emergency Braking

An emergency braking manoeuvre with this tyre has caused the tyre to rapidly wear through the complete casing causing the tyre to deflate.
     
  Cuts

Sharp objects can cause considerable damage rendering a tyre unserviceable.
     
  Impact Damage

This is damage caused by an impact to the sidewall. The bulge or "egg" indicates localised casing damage.


How often do I really need to have my wheels aligned?

If the wheels on your vehicle are correctly aligned when the vehicle is manufactured at the factory, they should not change alignment until something in the suspension wears out or is damaged. Alignment doesn't change. The only thing that changes it is wear or damage. Hitting a pot hole or a thousand pot holes won't knock your suspension out of alignment unless you hit something hard enough to actually bend metal. That really doesn't happen very often, so having the wheels aligned periodically is a waste of money.


How to read tyre sidewall?

The side of your tyre — known as the sidewall — contains all of the information you need to know about your tyre. Whether your tyre comes from Goodyear or some other manufacturer, all tyres are required to show this information.

Tyre Type defines the proper use of the tyre. For example, the "P" on the tyre shown here means that this is a passenger car tyre. If the tyre had an "LT" designation, the tyre would be for a light truck.

Tyre Width is the width of the tyre measured in millimeters from sidewall to sidewall. This tyre width is 215 millimeters.

Aspect Ratio is the ratio of the height of the tyre's cross-section to its width. On our example, 65 means that the height is equal to 65% of the tyre's width.

Construction tells you how the layers of the tyre were put together. The "R" stands for Radial which means the layers run radially across the tyre. A "B" stands for bias construction which means that the layers run diagonally.

Wheel Diameter is the width of the wheel from one end to the other. The diameter of this wheel is 15 inches.

Load Index indicates the maximum load in pounds that the tyre can support when properly inflated. You'll also find the maximum load elsewhere on the tyre sidewall, both in pounds and kilograms.

Speed Rating tells you the maximum service speed for a tyre. "H" means that the tyre has a maximum service speed of 130 mph. This rating relates only to tyre speed capability and is NOT a recommendation to exceed legally posted speed limits.

DOT means that the tyre complies with all applicable safety standards established by the U.S. Department of Transportation (DOT). Next to this is a tyre identification or serial number — a combination of numbers and letters up to 12 digits.

UTQG stands for Uniform Tyre Quality Grading, a rating system developed by DOT. For more information on UTQG.


Equivalence Between The Speed Index And The Corresponding Maximum Speed

Speed Symbol Maximum Speed Km./Hr.
M 130
N 140
P 150
Q 160
R 170
S 180
T 190
U 200
H 210
V 240
W 270
Y 300
Z Over 240


Equivalence Between the Load Index and the Determined Load Index For The Tyre

LOAD INDEX MAX. LOAD (KG) LOAD INDEX MAX. LOAD (KG)
70 335 97 730
71 345 98 750
72 355 99 775
73 365 100 800
74 375 101 825
75 387 102 850
76 400 103 875
77 412 104 900
78 425 105 925
79 437 106 950
80 450 107 975
81 462 108 1000
82 475 109 1030
83 487 110 1060
84 500 111 1090
85 515 112 1120
86 530 113 1150
87 545 114 1180
88 560 115 1215
89 580 116 1250
90 600 117 1285
91 615 118 1320
92 630 119 1360
93 650 120 1400
94 670 121 1450
95 690 122 1500
96 710    


How much air should I put in my tires?

It depends on the vehicle application, the size of the tires, how much weight is on the tires, and whether fuel economy is more important to you than a smooth ride.

Listed in the owner's manual or on a decal in the glove box or door jamb in every vehicle are the recommended inflation pressures from the vehicle manufacturer. For most passenger cars, minivans and minipickups, the recommendations range from 27 to 32 psi. For fullsize pickup trucks and sport utility vehicles, the recommended inflation pressures tend to be about 5 to 8 psi higher to reflect the larger tire sizes and greater weight of these vehicles.

It's important to note that the recommended inflation pressures may differ for the front and rear tires.

The manufacturer's recommendations are not necessarily the optimum inflation pressure for your tires, but are generally the best for all-round driving. Adding a couple of extra pounds of pressure will decrease the rolling resistance of the tires and make a slight improvement in fuel economy -- but it will also make the tires harder which in turn may cause a somewhat rougher or harsher ride.

If you're carrying a lot of extra cargo, car pooling, hauling a lot of stuff in the back of a pickup or towing a trailer, a few extra pounds of pressure would be recommended to offset the added weight. Add the extra pounds to the rear tires.

WARNING: Never exceed the maximum inflation pressure specified on the sidewall of the tire. This number is the maximum pressure the tire is designed to safely handle. Higher pressure increases the risk of tire damage (when hitting a bump) or tire failure.


Is it still necessary to rotate the tires every so often?

There are two schools of thought on this subject. Rotating the tires, which is recommended by all tire manufacturers, involves changing their position on the vehicle from one wheel location to another. This helps to even out tire wear between all the tires so the tires last longer and do not develop abnormal wear patterns. This may be recommended every 8,000 to 15,000 miles.

On front-wheel drive cars and minivans, the front wheels tend to wear at a much faster rate than those on the rear. After 50,000 or 60,000 miles of driving, the front tires may be worn out while the ones on the back may still have half or more of their tread life remaining. By rotating the tires front to rear and side to side, differences in wear patterns between the wheel locations spreads the wear out and more or less wears the tires evenly -- or so the theory goes. Consequently, tires that would have lasted only 50,000 or 60,000 miles on the front of a front-wheel drive car may last 70,000 or 80,000 miles. But on the other hand, the tires on the rear that may well have gone 100,000 miles only last 70,000 or 80,000 miles.

Those who say rotating tires is a waste of time argue that it makes more sense to replace the front tires on a front-wheel drive car or minivan when they wear out, but to leave the back tires alone -- especially if you're putting a lot of miles on the vehicle or plan to keep it a long time. The back tires will probably last as long as two sets of front tires, so in the long run you end up buying the same number or possibly even fewer tires by not rotating. Plus, you've saved the time and money that would have been spent on rotating the tires.


Reference :
  1. http://autos.yahoo.com/owning/maintain/repairqa/
  2. http://www.goodyear.com.jm/tire_know/tire_learn/
  3. http://www.kwik-fit.com/changing-tyres.asp
  4. http://www.etoz.com.my/engine-oil-knowledge.html
 
     
 
 
 
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