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Is it really necessary to "break-in" a Prius? I bought my 2004 a few days ago from a dealer more than 100 miles from my home and drove it back at an average of almost 80 mph (a combination of glee and curiosity motivated the speed). I almost never came near flooring the pedal, but after reading the owner's manual, I have been more delicate lately and am driving very conservatively. There are two distinct schools of thought about automobile breaking-in periods. Some mechanics swear that if you drive slowly when the car is new, the ultimate top speed will be reduced. Others swear that the life of the engine will suffer unless you allow the pistons to "seat" properly. Have I done permanent damage to my new car or is the "break-in" period just a precautionary ritual? By the way, after driving a series of Jaguar XJ-S's for 17 years, and anticipating considerable compromises when I purchased the Prius, I am pleased to report that I have had the time of my life behind a wheel these past few days. The 2004 Prius is a joy.
 

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It's hard to know for sure if you damaged your car by driving 80 MPH during the break in period. The effects, if any, are probably pretty small though since we haven't heard about other owners having major problems from this.

Driving slow during break in almost certainly won't limit the top speed since that's controlled by the computers. You're not allowed to approach the "real" red-line of the engine.
 

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Generic break in recommendations are very similar across most makes and models:
First 1000 miles:
Avoid full throttle.
Avoid steady sustained speeds.
Brake gently.
Don't race a cold engine.

My 04 is at approx. 2500 miles, hasn't used a single drop of oil (yay!!) and the oil is the color of Sue Bee honey (like new!).
 

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My 04 is at approx. 2500 miles, hasn't used a single drop of oil (yay!!) and the oil is the color of Sue Bee honey (like new!).
So, are you going with the recommended 5000mi change or with the 7500mile change as per the classic? I'm probably going to do the 7500.
--evan
 

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Decreased Maintenance Intervals

When I bought the car last week, the dealer brought to my attention that the normal driving scenario oil change mileage decreased from 7500 to 5000 miles in the Toyota Maintenance Guide and even went as far as recommending an oil change every 2500 miles. I wonder if that's a gimmick now that scheduled maintenance is no longer paid for. However, he added that if the oil looks fine, then you can go longer, but my understanding is that 7500 miles is now too long of a distance to travel on one oil change. Happy Driving.... :D
 

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I think the 5000 mile rec is a gimmick....let's see, same ICE as the classic, should run less with the more efficient battery and electric motor. The only thing that's really changed is that Toyota is no longer paying for the oil changes. If 7500 was ok on the Classic then it certainly should be OK on the '04...
--evan
 

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The thing with oil changes is - you should stick with 7500 mile rule unless you live in a harsh climate (desert - very dusty - very hot often) in which case you should modify your schedule as needed - per your dealer's recommendation.

Toyota dealers don't just sale cars, they sale service because the car is often very reliable and doesn't need a lot of extra service. So do what the owner's book says and politely let the dealer know that you're following Toyota's direction in this case. Also, don't forget about the massive power train warranty our car has.
 

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Hi Jeff12. My belief is; if the manual for the 2004 says change the oil every 5000 miles, then change it every 5000 miles. I'm sure Toyota would more than honor its warranty, but there was a time when car manufacturers would reject claims if they could prove warranty requirements were ignored. I think a little of that is still going on in some areas. Insurance claims for example. :wink: Whatshisname
 

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efusco said:
I think the 5000 mile rec is a gimmick....let's see, same ICE as the classic, should run less with the more efficient battery and electric motor.
It is not the same ICE at all. You have not read your Prius 2004 whitepaper pages 14 and 15 :) (specialreports_12.pdf).

In conventional engines, because the compression
stroke volume and the expansion stroke volume are nearly
identical, the compression ratio ((compression stroke volume
+ combustion chamber volume)/combustion chamber volume)
and the expansion ratio are basically identical. Consequently,
trying to increase the expansion ratio also increases the
compression ratio, resulting in unavoidable knocking and
placing a limit on increases in the expansion ratio. To get
around this problem, the timing for closing the intake valve is
delayed, and in the initial stage of the compression stroke
(when the piston begins to ascend), part of the air that has
entered the cylinder is returned to the intake manifold, in effect
delaying the start of compression. In this way, the expansion
ratio is increased without increasing the actual compression
ratio. Since this method can increase the throttle valve
opening, it can reduce the intake pipe negative pressure
during partial load, thus reducing intake loss.

High Functionality

VVT-i (Variable Valve Timing-intelligent) is used to
carefully adjust the intake valve timing according to operating
conditions, always obtaining maximum efficiency. Additionally,
the use of an oblique squish compact combustion chamber
ensures rapid flame propagation throughout the entire
combustion chamber. High thermal efficiency, coupled with
reductions in both the size and weight of the engine body
through the use of an aluminum alloy cylinder block, and a
compact intake manifold, etc., help improve the fuel efficiency.

Output Improvement

The engine's top revolution rate has been increased
from the 4,500 rpm in conventional engines to 5,000 rpm,
thereby improving output.Moving parts are lighter, piston rings
have lower tension and the valve spring load is smaller,
resulting in reduced friction loss. Furthermore, the increase
of 500 rpm produces faster generator rotation, increasing the
driving force during acceleration and further improving fuel
efficiency.
 

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Re: 2004 Prius Oil Change Period

I believe that the increase, from 4,500 rpm to 5,000 rpm, for the 2004 engine, is the main reason that the oil change period was reduced from 7,500 to 5,000 miles. Since the engine can rev higher and work harder, it would make sense to change the oil more frequently.
 

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Toyota has SERIOUS engine damage liability over oil gelling, which they at first denied. They 5K interval is far from a "gimmick", there were V6's that had oil turn to a solid.
I'm going to Mobil 1, like in all my cars, at 5k.
The Miller cycle intake timing has NOTHING to do with oil life.
 

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I believe that the increase, from 4,500 rpm to 5,000 rpm, for the 2004 engine, is the main reason that the oil change period was reduced from 7,500 to 5,000 miles. Since the engine can rev higher and work harder, it would make sense to change the oil more frequently.
Ok, that makes some sense to me. I haven't been convinced that this is a different ICE yet, just that they changed the maximum RPMs...anyone verify that it is a new engine?

I'll reconsider the 5000 mile issue. Per the ongoing discussion on synth vs dino oil on the Yahoo site I'm still undecided on which way I'll go on that issue. My heart wants to go with synth, but my mind and the hard data are saying it doesn't matter and that dino is cheaper.
--evan
 

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The ICE in the Prius is basically the same as in the 2001 Echo I drove before I got my 2004 Prius. It is one tough little engine and noted world-wide for reliability. I used Mobil 1 5w-30 with a 7500 mi change interval and was amazed at how clean the used oil was in comparison to what used to come out of my Dodge truck. Since Toyota calls for 5000 mi. changes in the Prius, that's what should be done, at least until the warranty period has passed, then it's your call. As far as the use of synthetic oil - I have used Mobil 1 for many years. It is definitely the best oil available OTC. It keeps engines very clean and helps to improve fuel economy. I think most people here are interested in getting the most out of their Prius and a few extra dollars to provide the best ICE protection available won't bust anyone's budget in the long run. I do all of my own oil changes so I am putting the money saved from the oil-change place into better oil and longer life for my car.
 

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Jerry,
The problem is that there is no proof (zero, nada) in the form of controlled studies or even observational studies of large fleets that shows any advantage of synth over dino oil. You DO hear lots of people that happen to be true believers in synth make claims, like yours, that it keeps the engine cleaner and works better.

I'm a scientist, I'd definately use synthetic if there was a shred of scientific evidence to show that it is definately better. I DO want to get the most out of my car. I DO NOT want to pay more than necessary for a product that isn't any better. Again, there's been a long discussion on this on the Yahoo Forums, I searched the Car Talk Forums and Sam the oil guy (or something like that) site looking for anyone who could show a single legitimate study that gives any convincing evidence that synthetics improve either performance or engine life or decrease wear over dino. So far only synthetic oil manufacturers ads seem to show that.

If you have such a study or know of a source of that information I definately want to see it...I'd make the jump in a heart beat. As it is I still 'might' use it just because. But the physician in me is crying out for evidence to support doing it. BTW, the 'few bucks' ads up, just as it does for fuel consumption.
 

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Synth vs. Dino

I do seem to recall a study done by Consumers Union a.k.a. Consumer Reports on a fleet of taxi cabs in New York City a few years back. Based on their results I've never felt the urge to use synth. To my recollection there were no significant benefits to warrant the extra cost.
 

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I have to agree with you. Although I've actually seen instances where running synthetic hid problems - example: a particular car that I use to own had some problems with blow-by which resulted from the low tension rings used - those who used synthetic didn't know they had a problem until it was too late because the synthetic would not burn as easily as the dyno-juice. Ultimately - cars suffered from destroyed catalytic converters.

We also don't run synthetic in motorcycles with a wet-type clutch because it causes slippage - unrelated :wink:

efusco said:
Jerry,
The problem is that there is no proof (zero, nada) in the form of controlled studies or even observational studies of large fleets that shows any advantage of synth over dino oil. You DO hear lots of people that happen to be true believers in synth make claims, like yours, that it keeps the engine cleaner and works better.

I'm a scientist, I'd definately use synthetic if there was a shred of scientific evidence to show that it is definately better. I DO want to get the most out of my car. I DO NOT want to pay more than necessary for a product that isn't any better. Again, there's been a long discussion on this on the Yahoo Forums, I searched the Car Talk Forums and Sam the oil guy (or something like that) site looking for anyone who could show a single legitimate study that gives any convincing evidence that synthetics improve either performance or engine life or decrease wear over dino. So far only synthetic oil manufacturers ads seem to show that.

If you have such a study or know of a source of that information I definately want to see it...I'd make the jump in a heart beat. As it is I still 'might' use it just because. But the physician in me is crying out for evidence to support doing it. BTW, the 'few bucks' ads up, just as it does for fuel consumption.
 

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A good place to visit to learn everything you could ever want to learn about oil - and more- is http://www.bobistheoilguy.com. There are some very well versed guys there and lots of info and observations. I plan to switch my Prius over to Mobil 1 5w-30 next Sunday. I should have about 1600 miles on it by then. I know I will feel more confident that I am taking the best care possible of my car after using Mobil 1 for many years> We pulled the valve covers on a 1994 Dodge Dakota 2.5L4 at 125,000 mi, just before I traded it in on my ECHO, and the engine looked brand new. IMHO a clean engine is a happy engine!
 

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I don't know why you guys won't read but I will summarize the two changes in two sentences and bullet them, how about that?

* They changed the ICE's head shape so that the burn distributes evenly.

* They changed the valve timing so the valve actually stays open for half of the compression stroke (no small change) so the combustion stroke would be, in effect, allotted more time.
 
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