Gas Prices

I dont change my oil at 3000 miles . No way no how..
I know it is not necessary.. But most people DO just that and so I was bringing up that expense as well.

chai.. you have my exact car.

I change the oil.. ehh... about every 10,000 miles.. ?
If I do a lot of highway driving, I may change it more..
I am going to , for example,change it 3 or 4 days before we go to NM.
But not when we get back.
I can -feel- the difference in my cars performance when it is time to change the oil. It gets.. sluggish.. Not BAD.. but I notice it. So I change it. Voila.

Same for transmission fluid.
I have changed it three times in its 85,000 mile life span.

Your car's performance would not be noticeably affected, when it was time to change the oil.

You would not notice it being sluggish, unless the oil had broken down severely so as to lose a significant amount of its viscosity and lubricity. This is extremely unlikely indeed, unless you never change your oil.

It's all in you imagination!

so then why do I feel a performance difference in my car ?

PMS?

Dont make me come over there

You don't feel a performance difference, you have made it up.

Many people spend a small fortune on all sorts of so-called "performance accessories" for their vehicles.

So-called "high-flow air filters", "cold air intakes", "performance exhaust systems", the list is endless. Many people are deluded into believing these items have real world advantages. The after market suppliers are more than happy to feed the flames of fantasy.

For $22.50 you can find out the true condition of your oil:
http://www.blackstone-labs.com/

But....... why would you do that?

You'd then spoil the fantasy that your oil has degraded so badly, that it can no longer provide the basic lubricity and viscosity required for your engine to supply its performance rating.

shewolfnm you must save your engine from its certain fate with the devil oil

Understand the context specific argument here is not that your oil should or should not be changed at the given interval you are choosing, but that that your oil has not degraded so badly, that it can no longer provide the basic lubricity and viscosity required for your engine to supply its performance rating.

<guffaw>

This is closer to the real truth; and believe me, I love my engines, I've got enough of them that's for sure!

http://www.projo.com/projocars/content/ca_oilchanges_03-15-08_F296TAF_v7.1d6c6f3.html

You're still lucky - $ 4.05 here in California - Monday through Thursday,
Friday/Saturday/Sunday it can vary from $ 4.25 to $ 4.35

Concerning the oil change: doesn't it say in the car manual how often
one should change it?

I only notice it when the oil light is blinking, but I service the
car whenever the service light is blinking. That should do it!

You are right C.J.- that is an outrageous price, still makes me sick though.

To answer your first question: One of the benefits of oil analysis is that you can usually get more use out of your oil and go longer in between oil changes. But because all engines wear differently, the only way to tell for sure whether you can do so is to analyze the oil.

As to you noticing the oil light is blinking, if by oil light you mean oil pressure light then in general that light should never come on once the engine is running.

As to you noticing the service light is blinking, if by service light you mean the oil change light, then see my text above about the benefits of oil analysis.

just here to complicate things, my porsche has no oil sump but it does have an oil cooler and attendant oil hoses. it is designed to burn 1 quart of oil per 1,000 miles so topping off the oil is regular event, the porsche holds 12+ quarts and there are 3 gauges on the dash to keep track of oil temp/pressure and levels which are all critical to the proper operation of the motor.

A dry sump is better than a dry hump I guess!

Also, the new Mazda RX8 uses some oil in its natural state to keep the apex seals happy.

But oil consumption (if it's within design parameters) does not in and of itself imply the need for more frequent oil changes.

No not really. If my oil is low, an oil can sign comes on and flashes,
if I need to go for service, I have a sign blinking that read" Your service
is due now", or "your next service in ........miles" I was told not to
do anything, unless the lights are blinking.

I'm not sure what you are saying "no" to...........nor what vehicle you are referring to.

But...... very-very few passenger street vehicles have an oil level light, it's almost always oil pressure .

You may be a bit confused/misled.

Also your "service is due now" , "your next service in ...." light is nothing more than a glorified trip odometer, sorry to say. It is in fact meaningless or worse, as it senses nothing about the engine or the oil.

Again, your oil pressure light (oil can icon) or otherwise should not come on once the engine is running.

Yes, it's the oil pressure icon that comes on when the oil pressure is low,
even when the engine is running, but it only happened once, so I'm fine.

If there was any harm done by running low oil pressure, it's too late to do anything about it now. Whoever you have as a mechanic is completely full of BS however, if they told you they are sure no harm was done.

Plain bearings however, do not require a pressure feed to function.

Oil pressure per se, as typically measured, is not an indication of a plain bearing's happiness.

I had an Impala rental that told me to change the oil filter. I didn't, but assume it was comparing inlet to outlet pressure.

No, almost for sure, it also would have been a glorified trip odometer, as discussed.

All oil filters have a bypass valve built into them so that if they reach a preset level of decreased filtration efficacy, said internal bypass valve opens to allow the oil to continue to circulate.

This is considered the lesser of two evils, the worse evil of course being restricted oil flow and all the perils of such a condition.

You give the auto companies far too much credit by assuming things like comparative oil pressure algorithms etc; the major purpose of these engine service reminder idiot lights, is to get you back in the shop by counting down the miles!

The truth of the matter is, in many cases, the amount and quality of the engine data now found on a modern passenger car's dash is weaker than it was thirty years ago, OBDII notwithstanding!