69
votes
17answers
107k views

Does Downshifting (Engine Braking) Cause Extra Wear and Tear?

Does the act of downshifting to slow your vehicle down have any negative side affects? I don't downshift more than one or two gears at a time and I let out on the clutch slow enough that I don't rev ...
63
votes
9answers
26k views

What are the benefits of premium (high octane) petrol?

Here in the UK it's common for petrol (gas) stations to offer both regular and "premium" unleaded petrol. The premium stuff is (naturally) more expensive, and I've often wondered what the actual ...
62
votes
9answers
41k views

Does the amount of fuel in the tank matter?

As long as there is some fuel in the tank, does the fuel level matter? In other words, is it advisable to make sure the tank is mostly full most of the time, or is this just silly? In other words, are ...
55
votes
20answers
14k views

How can I keep stray cats off my car?

We have a lot of stray cats in my neighborhood and they possess an uncanny ability to know when a car has been cleaned for them to sit on and enjoy. Needless to say, the dirty, dusty paw marks they ...
55
votes
16answers
249k views

Should I resurface or replace my rotors everytime I replace brake pads?

I have heard it is proper practice to replace or resurface your brake rotors every time your do a brake pad replacement. Does this need to be done every single time or is it overkill? Maybe it is ...
53
votes
14answers
10k views

Are classic cars safe?

Are classic cars safe? I am interested to know the differences between modern vehicles and vehicles of old from the 1960s. In the event of an accident, how does a classic vehicle compare to a ...
49
votes
6answers
2k views

How to maintain a sometimes-used vehicle?

My daily commute changed from 9 miles to 9 feet when I started working remotely. That means I very rarely drive my car much. After a particularly hectic month, I didn't drive for about 4 weeks and ...
47
votes
7answers
7k views

What to check when buying a used car?

I'm looking to buy a used car. What do you think I should check (mechanically) before buying it (especially if it's diesel)?
44
votes
6answers
163k views

Why does my A/C blow foul smelling air when it first turns on?

Most of the time when I first turn on the A/C in our 2008 Toyota Sienna, the air that blows out has a very distinct chemical - nasty smell. After a while it seems to go away. I'm not sure if I just ...
42
votes
5answers
113k views

How long does it take for gas to go bad?

Approximately how long does it take for unleaded gasoline in the tank and fuel lines to become unusable in a car that is not being used? What causes this, and what can be done to prevent or remedy ...
40
votes
6answers
3k views

What is the most efficient method of getting your car unstuck from snow?

If your car is stuck in snow and you don't have any chains, what can be done to get it out? This can be an unnerving problem to have and it happens pretty easily with normal driving on ice. You wind ...
38
votes
6answers
7k views

Why do heavy vehicles almost always use diesel engines?

I have always wondered why heavy vehicles such as large trucks and buses almost always use diesel engines, whereas in light cars there is a choice between diesel and gasoline engines. Engine ...
36
votes
14answers
8k views

How do I save myself from a sinking vehicle?

Every year in Arizona there are monsoon storms and somebody inevitably get's killed in a car that is sinking in water. It appears the primary issue is getting free from the vehicle. After that, ...
35
votes
4answers
33k views

Reviving a vehicle that has been idle for a long time

Some related topics: How to maintain a sometimes-used vehicle? How long does it take for gas to go bad? The first related topic addresses preparing a vehicle for long-term disuse, and maintaining ...
35
votes
12answers
4k views

Best way to clean inside of windshield?

The inside of my windshield has a thin layer of grime. When the light hits it a certain way, it drastically reduces my visibility. I have used glass cleaner with clean microfiber car cloths and ...
34
votes
3answers
33k views

Is there a way to put Prius with dead battery into neutral?

I own a 2010 Prius. It has a dead battery, front facing forward in my garage. I do not have long enough jumper cables. I’ve searched the Internet. Did Toyota really create a car that cannot be put ...
32
votes
9answers
27k views

What actually happens when there is not enough oil in a car engine?

When a car is topped up with oil, it clear to most people that you are supposed to fill it to the recommended amount as specified by the manufacturer (normally on a dip stick). What exactly are all ...
30
votes
9answers
44k views

Is it necessary to 'burn in' or 'break in' a new car?

I've just bought a new 2011 plate car. I've heard stories of people 'burning in' engines for the first few hundred or couple thousand miles using methods such as: Not driving above 50 mph. Varying ...
30
votes
5answers
7k views

Is tire rotation important?

I just bought new tires for my car and included was free tire rotation every 7,500 miles for the life of the tires. I have heard many things about tire rotation, including: it's a worthless ...
28
votes
10answers
8k views

What is in fossil fuels that we can't mass produce?

Since fuel is made up of different molecule chains, my question is what is the reason we cannot create the same molecule structure and be able to reproduce the same structure in a lab so we don't have ...
27
votes
3answers
10k views

Jump starting a dead battery: Connect black wire to negative pole of battery or grounded metal?

Most of the advice I've seen for jump starting cars instructs to connect the black wire to a bare piece of metal on the car with the dead battery. However, I've always just hooked up both poles to the ...
27
votes
3answers
10k views

Difference between FWD/RWD/4WD/Part-Time 4WD/AWD?

I'm curious as to what are the particular difference between the various drive systems available in modern vehicles. FWD and RWD are pretty straightforward - Front Wheel Drive cars put the power to ...
26
votes
5answers
3k views

What are the benefits of a lightweight flywheel and why aren't they lightweight already?

This previous question explains what a flywheel does and why it is needed. That explanation means that the flywheel needs a certain amount of mass to do its job. However, an "upgrade" for many cars ...
26
votes
6answers
6k views

Do cars consume less fuel when in Neutral? [duplicate]

Imagine we're going down a hill and we're driving a manual car. There are two situations: If I put my car in neutral it will go downhill without any need for the injector to squirt fuel into the ...
26
votes
8answers
7k views

Do I really need to wash the outside of my car?

Some people say they wash the outside car every week as it makes the paint nice etc Are there any benefits of washing the outside of my car? Do I really need to wash the exterior of my car every ...
26
votes
7answers
259k views

what is the difference between DOT3 and DOT4 brake fluids?

What is the difference between DOT3 and DOT4 brake fluids? What could possibly go wrong if I use a (4 times cheaper) DOT3 brake fluid instead of the DOT4 which manufacturer recommends (but allows ...
25
votes
4answers
51k views

How far can I drive with 1 gallon too much oil?

I have way too much oil in my Acura TSX. Do I need to take care of it without turning it on or can I drive it to a service station? If I need to do it in place, I don't have the ramps or a pan or ...
25
votes
3answers
7k views

Static vs. Effective compression: Why does higher effective compression not require higher octane gas?

Background I've been trying to do a lot of research on boost lately because I'm planning on running a moderate turbo setup on my daily/light-duty-autox car in the future. I'm trying to get into the ...
24
votes
3answers
123k views

What does a water like drop coming out of the exhaust of the car signify?

Sometimes while driving in the traffic, I come across a car or two which would be dripping water-like drop from it's exhaust steadily in a break of 4-5 seconds. I tried to ask a couple of people at ...
24
votes
6answers
2k views

When is a cold air intake system beneficial?

Cold air intake must be one of the popular mods there is, and one subject to the most controversy as well. Manufacturers of such systems advertise 5-20 HP gains, yet there are claims that this mod ...
24
votes
2answers
7k views

Do I have an oil leak if I have to add oil?

I don't change the oil all that often (maybe every 8000 miles) and on my 10 year old car the oil light comes on and I need to add a quart or two (and then I start thinking I practically changed the ...
24
votes
1answer
12k views

Why does the reverse gear in manual transmission cars sound different

When I got a manual transmission car (2003 Kia Rio) I noticed that it makes a winding sound in the reverse gear. Here is an example video that I found that demonstrates the sound. ...
24
votes
1answer
3k views

What's the Purpose of Park on an Automatic Transmission?

When one wants to park a manual transmission (MTX) vehicle, one puts it in neutral, and engages the emergency / parking brake. With an ATX vehicle, the practice I've learned is to put it in Park, and ...
24
votes
5answers
5k views

What is the technical reason the engineer decided the motorcycle gear pattern as follows?

The gear pattern is selected by clicking a lever with your left foot, and is typically laid out as follows: 6th gear (if applicable) 5th gear 4th gear 3rd gear 2nd gear NEUTRAL 1st gear What ...
24
votes
2answers
2k views

How to deal with rust

I accidentally drove my car over a curb a while back. As you probably already know, the car suffered from minor scratches and dents on the bottom side, near the rear tyre. Now, I've noticed that it's ...
24
votes
1answer
2k views

Why are the blades of old car radiator fans unevenly spaced?

Fans that look like this: Is it to somehow help the balance of the engine?
23
votes
8answers
2k views

Are tyre repair kits a viable alternative for a spare wheel?

I would REALLY like to get rid of my spare wheel. The wheel is heavy and I need the spare wheel well for... other purposes. In my history of driving I never had to use the spare wheel, so it cost me a ...
23
votes
8answers
64k views

Will higher octane fuel improve gas mileage?

I've heard from some people that high octane fuel will increase gas mileage. Around here, we have the basic unleaded(87), mid-grade(89), and premium(93 or 91). I've been using the basic 87 unleaded ...
23
votes
6answers
86k views

Pros/cons of higher capacity car battery?

I'm shopping for a new car battery for 1998 Subaru Outback (2.5l). For the physical dimensions the battery has to match, I see some variance in capacity (Ah) rating, and in price too, of course. The ...
23
votes
3answers
3k views

Why does a gas engines torque and horsepower curve always meet at 5252 RPM?

I'm watching a TV show called Tech Garage and they just made the claim that an engines torque and horsepower curves always meet at 5252 RPM. Assuming this is true, why does this happen? Is it ...
23
votes
3answers
5k views

Will engine braking damage my transmission? How can I tell?

I drive a manual transmission '08 Honda Fit. On my daily 17 mile commute to work, there are three long hills that I can coast down, each about a half mile long. Going down these hills, I've done two ...
23
votes
1answer
2k views

Changing Firing Order in a 4 Cylinder Car

Backstory In motorcycling you can get cams that change the firing order and time from a traditional 1,3,4,2. It's was very common in American roadracing in the 1990's to hear 4 Cylinder engines that ...
22
votes
7answers
4k views

Why could my vehicle be shaking around 60mph after hydroplaning?

Yesterday, I was driving home in a storm and I ended up hydroplaning. My car, Hyundai Elantra Coupe 2014, spun a 360 landing me in the dirt on the side of the road. Luckily, no one was driving by me ...
22
votes
7answers
97k views

Is it safe to drive a car that has a broken suspension spring?

Yesterday I was driving home from work and heard a loud noise which I can only really describe as a "clang". After looking at it today, it looks like the spring for the front left (passenger side) ...
22
votes
3answers
4k views

Why do pickups and large SUV's use 4x4 and generally not AWD?

In almost every case I can think of, the larger vehicles with four wheel power are 4x4, and the smaller ones AWD. As far as my experience goes, AWD is much more convenient, and also works at least as ...
22
votes
2answers
2k views

What are the Advantages & Disadvantages of a Boxer engine?

I know that boxer engines are those which have pistons moving in the opposite direction. Also the fact that since they sit low the center of gravity is lower and causes better handling. Why dont ...
22
votes
2answers
2k views

Why do two-stroke engine exhaust pipes look so strange?

Two stroke gasoline engine exhaust pipes are shaped strange. They expand into a wide diameter and then shrink down to a very small diameter where the exhaust gasses emerge into the environment. Why ...
22
votes
1answer
445 views

5-Stroke Engines - What are these things?

What is a 5 stroke engine? Why aren't they using them in vehicles right now? Is this a new thing or has it been around for a while?
21
votes
8answers
5k views

What is my friend's wife not telling him (about this tire)?

So a friend of mine sent me this picture of a "blow out" that happened on his wife's car (some Infinity coupe). She said that it just happened all of a sudden with no warning. She says she pulled ...
21
votes
8answers
220k views

What is the difference between normal, platinum, iridium plugs?

What is the difference (besides price) between normal, platinum, and iridium spark plugs?

15 30 50 per page