02 PT Cruiser woes

And those full throttle sessions should be in a high gear with the car at speed, rather than at high engine speeds (RPM).

| > The Chrysler/Dodge owners manual recommends occasional "short" full throttle | > sessions every few miles for the 1st few hundred miles. (But not full | > throttle "starts"!!) | | And those full throttle sessions should be in a high gear with the car at | speed, rather than at high engine speeds (RPM). |

Not sure that is true. Unless you have the auto stick option locked into

Yes, this is like the telephone company when they say that "the minimum threshold that it is OK for a phone line to support is 2400 baud modems" while behind the scenes they are spending millions of dollars on new switching equipment that can support 56k dialup.

In short, the quart/1000 is a pure sales and marketing figure, that has no relation to the actual oil consumption figure that the engine designers aim for. It exists because statistically your occasionally going to have an engine right off the assembly line where all the piston rings in it are at the absolute minimum diameter allowable in the tolerance and pressure and the cylinder walls of all cylinders are at the manimum in tolerance, ditto for the valves, etc. plus throw in a small oil leak that only drips when the oil is under pressure - and the automakers don't want to have to spend the money replacing it, because from their view it's cheaper to throw an extra 20 gallons of oil through the engine during it's lifetime than replace the engine.

If the engine designers actually used this as a real baseline, then due to manufacturing variances, the automakers would be paying out thousands in oil leak warranty claims because you would see quart/250 or quart/500 mile burners rolling off the line.

While it is of course not going to be possible to verify this (since these figures are held in secret by the automakers) clearly the engineering baseline is about 20% less than the amount of oil held between the MAX and MIN oil fill lines on the dipstick over the recommended oil change interval.

In short, if the dipstick MAX and MIN is a quart, and the oil change interval is

The reason for this is obvious if you think about it. It is because once the oil level drops below MIN then the engine is sucking air, and self-destructing. The automakers have to have as a goal the maintaining of that oil level ABOVE the MIN line during the warranty period, as long as the manufacturer's recommended oil change interval is followed.

Now you can point to all the exceptions in the warranties you want that supposedly let the automakers off the hook if engine damage that happens during warranty is attributable to low oil level. However, these exceptions only help prevent the automaker from paying out on the 1-2% of claims that would result on those odd-man-out engines that just happen to be heavy consumers of oil - because there aren't enough of these for the customers to be any trouble.

But imagine if an autmaker produced an engine that BRAND NEW off the assembly line, 80-90% of the engines ran at quart/1000 miles consumption, the MAX/MIN difference on the dipstick was a quart, and the oil change recommendation was every 5000 miles. You would have a class-action lawsuit certified within a few years due to all the angry owners of engines that wore out at the 50K mark, to say nothing of the terrible publicity that would ensue.

And imagine also the damage it would due to fleet sales. Rental car companies today almost all of them are doing "unlimited" mileage and scenarios where people fly in to an airport then rent a car and drive 300-500 miles a day are not uncommon, and you can assume that no car renter is going to give a damn about oil. At a quart/1000 miles, you would have rental cars being sawn to pieces on dry bearings right and left.

And this may actually be conservative anyway because the automakers are responsible for _emissions_ components up to 80K miles, and extra oil in the combustion chamber clogs cats and 02 sensors, they may actually be shooting for a far lower oil consumption figure to get out of paying for those components under warranty.

:-) Cute. I personally see nothing wrong with a quart/3000 miles, but that is because I change my own oil at 3000 miles and use dino oil. (OK, now I'm going to get lecture from the Amsoil folks) I believe that 3000 miles/dino oil is the current "conservative" recommended oil change interval.

Ted

Ford? Talking about oil consumption? Thats a hoot, after their disaster letting the 5.4L Modular get on the market with inadequate oil control rings and poor piston design! They've got it down to manageable levels now, but the 5.4 was an oil hog its first several years on the market, and it WASN'T the PCV system.

And my Chrysler engines (both the '73 and the '93) use no more oil than any Toyota engine I've ever seen.

The published ring clearances and bearing clearances on my '93 3.5L v6 are IDENTICAL to the ones on my '73 318 and my '69 440.

And none of them burn oil, either. The older ones *leaked* oil until I replaced the cork/rubber gaskets with modern neoprene ones, but they don't burn oil.

The only "big old v8s" that have "sloppy tolerances" are a) the ones built in the early 50s or prior, and b) the ones people see today that have been run to the ground on substandard or never-changed oil.

I add one quart (or less) per 7000 mile oil change interval on my '73,

That's another topic of debate among armchair mechanics. The counter-argument is that you SHOULD take it to redline during breakin, but never hold it at high RPM for any extended period. The theory being that because connecting rods stretch slightly and crankshafts bend slightly, the only way to break in the last few thousandths of piston travel up the cylinder wall is to take it to full RPM.

Sales and marketing? I've never heard oil consumption advertised. It is a warranty-based parameter.

I never said it was a design target.

That's not clear at all. The design target might be no oil consumption at all or it might be something different. I don't know and you don't know either unless you are an automobile engine designer or know one well ... and that assumes they would tell you even then and risk their job.

Except that many engine makers no allow oil changes of 7,500 miles...

I don't think many engines suck air at 1 quart low. I'm not sure what the minimum is before serious damage occurs but I've seen a few cars that were run with the level completely off the bottom of the dipstick with no obvious signs of distress.

I know more about airplane engines than car engines and I don't know that you can make any extrapolations from one to the other, but my last airplane had a Continental O-470 that held 12 quarts when full, but would run down to 2 quarts, yes, TWO quarts before failure occurred.

Matt

Geez, Matt, imagine what you could do if you only had a clue.

doc

Jiffylube wants you to change your oil every 3,000 miles. They make a _lot_ of money that way. If you burn a quart every thousand miles, then you'll get into their bays with only a quart or so left in your engine. That's not very smart for a company that depends on repeat customers,is it?

Burning a quart per thousand miles is definitely an indicator that something big is wrong with your engine. You should be able to go at least

Yeah, you can go 50,000 miles without a change, in a decent engine. Not a good idea, but attainable, if you're not losing a quart per K like you are.

You have major engine problems, my friend, and oil consumption is the the least of them.

doc

Total bullshit, of course. Still, it's the owners' car and this d*****ad will never pay you for doing what he suggests if he's goes wrong.

Always the problem with interenet experts: ask a question, you'll get an answer. You're money, their time. They'll always have more than you will.

doc

I can say with some certainty that it is NOT "zero oil consumption," at least not if the designer intends for the compression rings to be oil lubricated :-)

Frankly, I'm amazed at how little oil a nice tight piston engine will burn (and the fact that the current level was pretty much achieved 40 years ago), given that every few milliseconds the cylinder wall goes from being bathed in oil to being exposed to combustion.

According to you? Not according to some engine manufacturers.

You're one of them.

Really? My Grand Voyager just rolled over 140,000 miles last evening and has consumed a quart of Mobil 1 about every 2,000 miles since I bought it 6 years ago with 33,000 miles on it. Engine runs just fine as it has since I got it. When do you think this "big, big" problem will surface, Mr. Einstein?

And my Chevy truck has 82,000 miles and is 10 years old and uses a quart every 3,000 miles or so. Likewise, when will the "big bang" event occur with this engine?

Never said I was losing a quart per K. Are you able to read?

Maybe you are the major problem? :-)

Matt

It's already there. You've polluted the atmosphere with over 13 gallons of burned motor oil in the last six years. Not that you care, apparently.

Add another 7 gallons of burned oil to our mutual environment. Good going; you're up to 20 gallons, so far. I bet you don't bitch about gas prices, either. Why should you? You're a major contributor to them. At least your Chevy truck helps offset the damage by delivering crops to the market. I'm assuming you're not an urban truck-owner, of course, with the cutesey tonneau cover over the bed. Talk about conspicuous consumerism! Those posers really take the cake.

Yes.

I drive about 8,000 miles a year and change my oil twice in that time. I might burn 1/4 quart between changes, which comes out to about 1 quart every 16,000 miles. I'm not helping our mutual environment, but I'm having a significantly smaller effect on it than you are. And I care about that. You obviously don't.

If I'm the major problem, then the world's in pretty damn good shape, wouldn't you say?

doc

Ummm - excuse me - but where did that oil come from in the first place? How many gallons of gasoline do you burn into our mutual environment in a year's time? A lot more than 20 gallons I'd venture to say.

Bill Putney (to reply by e-mail, replace the last letter of the alphabet in my address with "x")

Nice attempt at dodging the issue. I've also polluted the atmosphere with ~4,864 gallons of gasoline during that time, so I don't think the

Again, inconsequential compared to the ~5,125 gallons of gas burned during that same time. I don't complain about gas prices, at least not much, as I lived for 4 months in England back in the 80s and learned what a real bargain our gasoline is. It costs less than bottled water for crying out loud.

Nope, don't deliver crops in my truck, but it is used as a truck. It hauls firewood, all manner of building supplies, carries a snowplow in the winter and has 4.56 r&ps for better low-speed work. I hardly drive a truck to show off at the mall. If I did, I wouldn't still be driving a 1994 with plans to drive it another 10 years if possible.

Then where'd you get the above statement from?

You haven't a clue about my environmental position. I change my oil at

Hardly. We have way too many self-righteous blow-hards already.

Matt

Thanks, Bill, you and I were thinking the same thing. I just posted a more thorough analysis on this exact subject for doc the wonder boy.

Matt

You can't be serious, can you?

Of course, but the car's designed for that. You knew that, didn't you?

Maybe not, based on your previous ridiculous question. You don't have many of your preconceptions based in reality, do you?

doc