- the official home of the Car Maintenance Bibles
Covering everything you need to know about, wheels, tyres or tires,
engine oil or motor oil, suspension (including springs and shock absorbers),
brakes (disc brakes and drum brakes) and general car maintenance.


Linking to or copying from The Car Maintenance Bibles

Can I make a copy of this site for my own site?

No. See the copyright page for more info. This site changes very frequently with additions and corrections. If you make a copy, it will instantly be out-of-date. See the change log for an idea of how frequently this site is updated.

Can I link to this site?

Yes. All information about linking can be found on the links page in the Reciprocal Links section at the top.

Wheels and tyres

Can heavier wheels affect my gas mileage (mpg)?

They can, yes. As well as contributing to a heavier vehicle, adding heavier wheels adds to the unsprung weight of the vehicle. This means the engine has to work slightly harder just to turn the wheels themselves, which can rob you of power and/or fuel efficiency. They'd have to be pretty heavy wheels to see a really noticable drop in mpg though.


What is ABS?

ABS stands for Antilock Braking System. It's a system designed to sense when the a brake is about to cause a wheel to lockup, and relieve the pressure on that brake automatically to keep the wheel turning. When the wheels are turning, not locked up, you have more control over your car.

My brakes judder when I press on the pedal. What's going on?

It's almost certainly warped rotors that are causing the problem. The first time around, it's always hard to tell what causes it. This sort of thing happens most often if you live in a mountainous area and use the brakes coming down mountain passes instead of relying on the drag from the engine. The other thing that can cause it is corrosion in the brake calipers. If the brake pistons aren't retracting properly into the caliper housings, then they will be binding slightly on the rotor when you're driving. Not enough to make any difference to the handling, but enough to overheat the rotors.
The solution is one of two things. You can either get the rotors re-machined where they're placed in a machining tool that shaves off some of the metal around the face of the rotor to make sure both sides are parallel and flat again. The other option is to buy new rotors.
Bear in mind that if you have them re-machined, they lose a lot of their heat capacity and its a lot easier to warp them again. It's also a lot easier to make a warped and re-machined rotor fail.

Engine Oils

Should my oil be black when I change it? It's a clear brown when I put it in but 3000 miles later, it's black. Why?

Don't worry about the engine oil turning black. It will lose it's golden-brown colour within a few hundred miles of being put in to the engine. That doesn't mean it's not working. Quite the contrary - it means it is working well. It changes colour as it traps oxidised oil, clots and the flakes of metal that pop off heavily loaded engine parts.

How long will new, bottled engine oil last for?

An unopened container should be good for about 3 years. See the engine oil bible page for full details on this topic.

Is there any way to tell if my current oil is mineral, semi- or fully-synthetic?

The short answer is 'no'. The long answer is 'yes' if you're prepared to extract a sample and send it to a chemical lab for analysis.


I've heard that Zmax/BoostR/Miracle-Wonder-Oil-O is a fantastic new engine oil additive. Is it really any good?

I don't know. I don't put additives in my oil for reasons outlined in the oil bible. As I don't use them any more, I can't post opinions about them, nor can I libel the companies concerned (these people have lots of clever lawyers). If that new product really is endorsed by Nascar or FIA, then why don't you ever see it on shirts and hats in the pit lane, or on mechanic's workbenches in the garages?

But Chad Richbastard's NASCAR team use Miracle Wonder Oil. Surely that's a good sign?

If I could get my engine rebuilt after only 400 miles of use, then I would endorse just about anything. Hell they could run sawdust in there if they strip it down after every race. Think about it - those engines typically don't do more than 400 or 600 miles. For the average car, that's about a week and half's driving.


I want to lower my car - should I buy new springs and shocks, or should I just cut the springs that are in there?

You should buy new springs and/or shocks. If you cut the existing springs, you will compromise their structural integrity. Once cut, they're no longer springs, they're just bits of metal. If they then fail at a later date, your insurance won't cover you because of a hack-job done on a critical part of your car.

I've just put sports springs on my car to lower it. Should I put sports shocks on too?

You should ideally buy springs and shocks as a matched set in a kit. When you get sports springs and use stock shocks, the shocks will tend to wear prematurely. They are designed to be a blend of comfortable ride and safe handling. By using shorter springs, the shocks are now overloaded. Getting a kit will mean that the shocks are matched to the length of springs.

Every time I go over a bump, my front suspension bangs / knocks / clonks. Why?

The most likely cause of this is the big rubber bush at the top of the front suspension mounts. If it has perished and worn out, then the top of the suspension is knocking against the inside of the suspension strut tower. Another symptom of this is if you park the car and turn the steering wheel from lock to lock, then move off slowly, there will be a "sproing" type noise as the suspension spring untensions. You should invest in new suspension bushes.

My car used to ride really nice. Now it's got 65,000 miles on it and it seems wallowy - the ride has gone to Hell. How can I solve this?

Most car companies won't tell you this, but shock absorbers and springs are pretty much end-of-life after 60,000 miles of average use. You need to change them. And if you do, then change them all at once. It's dangerous to do just the front, or just the back. Few people understand that shock absorbers make a lot of difference not only to the ride of your car, but the effectiveness of the brakes. With worn shocks, the wheels bounce and skip under braking. With good shocks they don't. Guesstimates as to the difference at 100km/h can be as much as 10 metres difference in braking just because of the shock absorbers.