Auto repair myths

[Zenmervolt]

Originally posted by: hanoverphist

Originally posted by: Zenmervolt

Originally posted by: hanoverphist
depends on the synthetic you use. in my dads harley, he uses a synthetic. when he took it in to get the heads redone, the mechanics told him he had the cleanest heads they had seen at 55k miles. hes never used anything but synthetic. ive seen engines that always had organic oils in them, and they arent anywhere near "clean" like his was and is, so id have to agree that synthetics help out.

My general rule is that air-cooled or turbocharged means use synthetic because of the greater tolerance for high heat. ("Air-cooled" really means "Oil-cooled" and for turbocharged engines the turbine housing can really heat oil.) In naturally-aspirated applications there's no real need for synthetic since it would take decades before the difference showed itself. Probably half a million miles at least. Superchargers are a toss-up.

ZV

being an industrial programmer and not a gearhead, i cant say either way without anecdotal evidence. we use synthetic oils in the big 125hp up to 400hp motors (electric) we use for water/ wastewater because they get almost twice the life out of them. thats about what i can say for sure. when you get into tolerances for heat and such, you lose me there. i know the mechanic said his engine had less wear on it than most bikes at 12k miles when he had his redone. he is a pro, so im going to take his word when he said it was due to him using synthetic and changing his oil regularly.

The Harley is air-cooled, so it will see pretty high oil temps, which causes sludge in conventional oil. Turbochargers can have problems from conventional oil coking in the bearing housings from high heat as well. Synthetic can withstand higher temperatures before it breaks down and when it does break down it creates an ash that is less damaging than the chunks of coke that traditional oil does.

Synthetic will undoubtedly last longer, but on a 5,000 mile interval regular dino oil will be more than sufficient for a street-driven car. Can generally even go to 7,500 mile interval on conventional oil with a quality filter.

ZV

 

[MrWizzard]

Originally posted by: BoomerD
Running premium in my Honda really improves the performance...

Uhhh but, oh you said your honda, some model honda's require Premium....

 

[thirdeye]

Originally posted by: Zenmervolt

Originally posted by: hanoverphist

Originally posted by: Zenmervolt

Originally posted by: hanoverphist
depends on the synthetic you use. in my dads harley, he uses a synthetic. when he took it in to get the heads redone, the mechanics told him he had the cleanest heads they had seen at 55k miles. hes never used anything but synthetic. ive seen engines that always had organic oils in them, and they arent anywhere near "clean" like his was and is, so id have to agree that synthetics help out.

My general rule is that air-cooled or turbocharged means use synthetic because of the greater tolerance for high heat. ("Air-cooled" really means "Oil-cooled" and for turbocharged engines the turbine housing can really heat oil.) In naturally-aspirated applications there's no real need for synthetic since it would take decades before the difference showed itself. Probably half a million miles at least. Superchargers are a toss-up.

ZV

being an industrial programmer and not a gearhead, i cant say either way without anecdotal evidence. we use synthetic oils in the big 125hp up to 400hp motors (electric) we use for water/ wastewater because they get almost twice the life out of them. thats about what i can say for sure. when you get into tolerances for heat and such, you lose me there. i know the mechanic said his engine had less wear on it than most bikes at 12k miles when he had his redone. he is a pro, so im going to take his word when he said it was due to him using synthetic and changing his oil regularly.

The Harley is air-cooled, so it will see pretty high oil temps, which causes sludge in conventional oil. Turbochargers can have problems from conventional oil coking in the bearing housings from high heat as well. Synthetic can withstand higher temperatures before it breaks down and when it does break down it creates an ash that is less damaging than the chunks of coke that traditional oil does.

Synthetic will undoubtedly last longer, but on a 5,000 mile interval regular dino oil will be more than sufficient for a street-driven car. Can generally even go to 7,500 mile interval on conventional oil with a quality filter.

ZV

Coking issues generally only occur in oil-only cooled turbos. Water/oil cooled turbos unless seriously abused shouldn't see this issue.

On a similar note, a common myth I've heard related to turbo cars is that it's bad to shut them down without a cool down period. Only true for an oil-cooled turbo, which most stock turbos are not.

 

[Zenmervolt]

Originally posted by: thirdeye
On a similar note, a common myth I've heard related to turbo cars is that it's bad to shut them down without a cool down period. Only true for an oil-cooled turbo, which most stock turbos are not.

Depends on the water cooling and on how one was driving.

My 951 has a separate electric pump for the turbo's water-cooling system and it will circulate coolant through the turbo for a minimum of 30 seconds after the engine shuts off and will come on for no less than 30 seconds if the temperature in the bearing housing reaches a threshold point. I never have to worry about letting the 951 idle after driving it.

My S70, however, relies on the engine's waterpump to circulate coolant through the turbo, which means that coolant flow stops as soon as the engine shuts off, period. While the coolant itself will absorb some heat it is still advisable with such systems to be out of boost for about 30 seconds before shutting off the engine. In most cases the normal parking process is more than sufficient and no extra idle time is necessary.

However, in both cases the oil sees higher temperatures than it would in a naturally aspirated car, simply due to the fact that it's circulating through the very hot bearing housing of the turbine.

Also (just to mention it, not directly related to your post at all), regardless of oil or water-cooling, one should NEVER shut off a turbocharged engine when it is under boost. The turbine's bearings require oil pressure for proper operation and is the turbine is still spinning fast enough to provide boost when the engine is shut off the sudden loss of oil pressure is very hard on the bearings.

ZV

 

[giantpinkbunnyhead]

Originally posted by: holden j caufield
wait a second aren't oil filters different. Fram is supposed to suck and mobil 1 actually filters. I think the Bob the oil guy did a comparison test and oils are different

You're right... but this thread is about myths, not truths. They myth was that all oil filters are the same.

 

[feralkid]

Spinners look cool.

 

[Ricemarine]

Originally posted by: Slickone
Using the A/C will use up the freon (I've had females tell me this).

Interstate driving, A/C on and windows up uses more gas than A/C off and windows down.

Wasn't that myth proven plausible on Mythbusters?...

 

[PingSpike]

The whistle goes woo woo.

 

[CFster]

When replacing brake pads, the rotors should always be turned.

 

[Pacfanweb]

Originally posted by: BoomerD
Other than grades, ALL oil is the same
ALL oil filters are the same.
Gasoline is gasoline, regardless of where you buy it.

Just buy the cheapest part you can. There's no difference between generic and "name brand."

1..Pretty much these days. Motor oil is motor oil, as long as you have the right weight for your engine. This wasn't the case back in the day.

2. Factory oil filters are superior to nearly all aftermarket oil filters, including the standard Frams. The Fram HP's are pretty close.
If you've ever seen a bunch of them cut open, you'll see what I'm talking about.

3. Gas isn't always gas regardless of brand, but sometimes it is.

 

[Pacfanweb]

Ha, nitrogen in tires.

What a complete load of B.S. that is. Does absolutely nothing but inflate the tire.

 

[shabby]

Originally posted by: Zolty
Blinker fluid needs changing every 15k miles, or until it turns a green color.

Oh snap, mine needs changing!

 

[Pacfanweb]

Originally posted by: foghorn67
Myth: Warming up the car will ensure everything is well lubricated on startup.
Exception: EXTREME cold weather.

With today's oils, there's really no reason to warm the car up at all. By the time your engine catches and you can physically let go of the key, the oil is everywhere that the pump pushes it to.
As you said, unless in extreme cold, you can start it and drive it like you stole it with no repercussions.

I've talked to a couple of Ford engineers that agreed with me on this when I was trying to get this argument settled.

 

[Pacfanweb]

Originally posted by: shabby

Originally posted by: Zolty
Blinker fluid needs changing every 15k miles, or until it turns a green color.

Oh snap, mine needs changing!

Don't forget your muffler bearings!

 

[wetcat007]

How do i get GoogleTV in my car?

 

[Kelemvor]

Originally posted by: randomlinh

Originally posted by: Kelemvor
Biggest myth of them all...

You should change your oil every 3000 miles. Of course the mechanics tell you that. You're paying them every time you have it done. Change the oil based on your manual, not on a mechanic.

I was wondering how long that would take to kick in. I just did a UOA on some penzoil platinum. 6500 miles and still good to go. I only change it because I'm paranoid and drive fairly hard. That and I autocross. Still not sure if it's worth going full syn still (granted PP is usually on sale for cheap after rebates)

I was surprised no one else had posted it before me. heh heh.

 

[wetcat007]

Originally posted by: Ricemarine

Originally posted by: Slickone
Using the A/C will use up the freon (I've had females tell me this).

Interstate driving, A/C on and windows up uses more gas than A/C off and windows down.

Wasn't that myth proven plausible on Mythbusters?...

Uh I'm pretty sure using A/C can cause you to use more gas, especially on smaller engines that have to work a bit harder to run the A/C. The noticeable drop in power on some cars general means your going to be putting the pedal down farther to move at the same rate hence using more gas.

 

[SparkyJJO]

Originally posted by: wetcat007

Originally posted by: Ricemarine

Originally posted by: Slickone
Using the A/C will use up the freon (I've had females tell me this).

Interstate driving, A/C on and windows up uses more gas than A/C off and windows down.

Wasn't that myth proven plausible on Mythbusters?...

Uh I'm pretty sure using A/C can cause you to use more gas, especially on smaller engines that have to work a bit harder to run the A/C. The noticeable drop in power on some cars general means your going to be putting the pedal down farther to move at the same rate hence using more gas.

Depends on the car really, how much the AC affects the engine. But at highway speeds the force of the air coming in the windows and slamming up against the back window of your car can actually create more drag on the engine than the windows up and AC on (again, depending on the engine). Of course the best is to have the windows up and the AC off, but it gets awfully warm inside when you do that

 

[foghorn67]

Originally posted by: Pacfanweb

Originally posted by: foghorn67
Myth: Warming up the car will ensure everything is well lubricated on startup.
Exception: EXTREME cold weather.

With today's oils, there's really no reason to warm the car up at all. By the time your engine catches and you can physically let go of the key, the oil is everywhere that the pump pushes it to.
As you said, unless in extreme cold, you can start it and drive it like you stole it with no repercussions.

I've talked to a couple of Ford engineers that agreed with me on this when I was trying to get this argument settled.

So I agree with you?

 

[Pacfanweb]

Originally posted by: foghorn67

Originally posted by: Pacfanweb

Originally posted by: foghorn67
Myth: Warming up the car will ensure everything is well lubricated on startup.
Exception: EXTREME cold weather.

With today's oils, there's really no reason to warm the car up at all. By the time your engine catches and you can physically let go of the key, the oil is everywhere that the pump pushes it to.
As you said, unless in extreme cold, you can start it and drive it like you stole it with no repercussions.

I've talked to a couple of Ford engineers that agreed with me on this when I was trying to get this argument settled.

So I agree with you?

Yeah. I was just expanding on the topic.

 

[Zenmervolt]

Originally posted by: SparkyJJO

Originally posted by: wetcat007
Uh I'm pretty sure using A/C can cause you to use more gas, especially on smaller engines that have to work a bit harder to run the A/C. The noticeable drop in power on some cars general means your going to be putting the pedal down farther to move at the same rate hence using more gas.

Depends on the car really, how much the AC affects the engine. But at highway speeds the force of the air coming in the windows and slamming up against the back window of your car can actually create more drag on the engine than the windows up and AC on (again, depending on the engine). Of course the best is to have the windows up and the AC off, but it gets awfully warm inside when you do that

You're both right.

At a constant speed, especially higher speeds, A/C is typically more efficient. When speed varries, A/C is less efficient. The A/C compressor carries a healthy amount of inertia and when a car is accelerating/decelerating often it is felt much more than when the car is at a constant speed.

To wetcat, remember that drag increases with the square of speed, double your speed and you quadruple your drag. All else being equal, you need 8 times the power to double your speed (4x power to overcome extra drag multiplied by 2x more power to double your speed). A slight increase in drag at 30 mph can have a huge impact at highway speeds.

ZV

 

[91TTZ]

1. You should never floor a car because it hurts the engine.

2. Putting in bigger fuel injectors gives a car more power.

3. Larger brakes make the car stop faster in normal driving situations.

4. A good tuner can tune the car so the HP and torque curves don't have to cross at 5252 RPM.

 

[WhoBeDaPlaya]

Originally posted by: Zenmervolt
4) If you have keyless entry and you lock your keys in the car, you can call a friend on your cell and have them use the spare remote to unlock your car if they point the remote at their phone and if you put your cell phone near the car.

LOL. Any EE worth their salt is gonna know that the severe undersampling and vocoding alone is going to fsck up that signal beyond recognition.

 

[mugs]

Edit: I was wrong

 

[WhoBeDaPlaya]

Originally posted by: MercenaryForHire
Obligatory "moar stickers = moar powar" entry.

My Honda had a "Type R" sticker you insensitive clod!