Engine break-in, wear, overhaul, and oil change

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The following outlines the factors I have observed determining maximum power, as of update 1.12.

It describes three variables, which multiply together to determine maximum power: "oil", "overhaul", and "engine".

Note that maximum power must be consistently assessed in a reliable spot, such as the rotating display screen in the garage. Power as shown in other places, such as the garage listing, may vary.
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• OIL

"Oil" has three stable states, and two decaying states transiting between them. The "neutral" state corresponds to oil that comes direct from the dealer, new or used, and has no multiplying effect on power. The "bonus" state corresponds to oil freshly changed or from an overhaul, and amplifies power by 5%. The "bad" state corresponds to oil in a car has been driven sufficiently far with the oil light on, and reduces power by 5%. "Oil" is reset by getting an oil change or overhaul.

The "bonus" state lasts for 200 km from oil change or overhaul, then "oil" decays at a rate of 0.05 %/km over 100 km to the "neutral" state, for a total change of 5% after 300 km.

The "neutral" state lasts until 5 000 km from acquisition of oil (oil change, overhaul, or new car), at which point the oil light comes on.

When the oil light comes on, "oil" decays at 0.005 %/km over 1 000 km to the "bad" state, for a total change of 5%.

Oil color changes from light to dark from about 300 to 600 km from acquisition.

"Oil" in a newly acquired used car seems to arrive at various points in the mileage progression of a new car, but does not appear to arrive past the end of 5 000 km "neutral" plateau, and thus an oil change alone will yield a 5% increase in power but no more. As with a new car driven between 600 and 5 000 km, oil may be dark but the oil light not yet on. If "oil" is at the end of the 5 000 km plateau, the oil light will be on and "oil" will immediately start degrading to the "bad" state. However, with a used car this may be the case well below 5 000 km on the odometer.

Oil change and overhaul are the only ways to get "oil" to the "bonus" state, and they also reset "oil" for its progression through the subsequent states.
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• OVERHAUL

"Overhaul" has two transiting states and two stable states. The "neutral" state has no multiplying effect on power, and the "bad" state attenuates it by 5%. "Overhaul" is reset by getting an overhaul.

New and prize cars arrive with "overhaul" at 3% below "neutral". They immediately start breaking in at .01 %/km over 300 km to reach the "neutral" state, at which time the option to overhaul opens (although to no immediate benefit beyond the included new oil).

The "neutral" state lasts until 5 000 km on the odometer.

It then declines at 0.000 5 %/km for 10 000 km to the "bad" state, for a total change of 5% at 15 000 km.

The state of "overhaul" in a used car is comparable to what it would be in a new car run for like mileage without overhaul, excepting a break-in period. Used cars do not have a break-in period, do not exhibit a power deficit if the odometer is below 300 km, and may be immediately overhauled (although to no immediate benefit beyond the included new oil). "Overhaul" in a car from the online dealership is comparable to that of a used car of like mileage, except that it is received at 0 km and cannot be overhauled (or get chassis maintenance) until it has 0.1 km or more.

Overhauling resets "overhaul" to the beginning of the 5 000 km "neutral" state (as well as changing the oil).
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• ENGINE

"Engine" may be considered the baseline for a car's power, modified by "oil" and "overhaul" to result in maximum power. "Engine" has two stable states and a transiting state. "Engine" cannot be reset.

The "neutral" state plateaus from 0 to 15 000 km.

It then declines at a rate of (about) 0.000 02 %/km (1% per 50 000 km) for (about) 250 000 km to the "bad" state, for a total loss of 5% at (about) 265 000 km.

As mileage increases beyond 15 000 km, an overhaul (even with the resultant benefit of the highest states of both "oil" and "overhaul") will yield progressively less maximum power.
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Notes

Power as listed in a dealership should be doubted by default, but may be accurate, and if so seems to represent a broken-in car under 5 000 km, without oil change boost.

The auto-save executed on exit from an event may precede the processing of some mileage effects, so that turning off the system without an additional save may result in the loss of some effects of driving from that event, e.g. the odometer may revert to the reading prior to entry.

Apparently:
• Different models behave the same way, except as noted for new & prize versus used
• Oil state doesn't affect engine wear
• Tuning doesn't affect engine wear
• RPM, including redline, doesn't affect engine wear

Karts behave differently. Generally, they don't change much and you can't do much to them.

I have heard but not investigated whether the X2010 behaves differently.
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I'm quite certain that PD started with a different mileage wear model, and that they may also have changed it multiple times through different versions. The impact of these successive version changes on a given car is very difficult to predict. This outline predicts performance of cars not driven ("switched") in previous versions of the game, including cars newly acquired since the latest update (and perhaps some number of versions earlier, too. Or not). If you've driven a car in a previous version you may have residual effects on power that give numbers inconsistent with this outline. Perhaps an overhaul would reset "overhaul" and "oil" and bring a deviant car's numbers into alignment. Or not.

Other possible factors affecting maximum power numbers:
• Rounding off
• Bugs, identified or otherwise
• Trading
• Version transitions
• Delayed or staggered processing after a race
• Entering a race
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Regarding the "GT5 Complete Car Database" (and related):
https://www.gtplanet.net/forum/showthread.php?t=134149&page=18

I would consider the reference power level for a car to be broken in, with "oil", "overhaul", and "engine" all in the "neutral" state. Simplistically, this means a car between 300 and 5 000 km, without a fresh oil change. This level is 3% above that of a 0 km car from the new car dealership or a prize card. This is often the power shown in the sales listing (new, used, or online), but not always. From this level, an oil change will yield +5%. Oil older than 6 000 km will yield -5%, mileage 15 000 km beyond new or overhaul will yield -5%, and total mileage beyond about 265 000 km will yield -5%.
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Related threads:

What we know about chassis/engine maintenance
https://www.gtplanet.net/forum/showthread.php?t=141569

Engine Overhauls Investigated.
https://www.gtplanet.net/forum/showthread.php?t=158452

Engine Wear?
https://www.gtplanet.net/forum/showthread.php?t=177967
 
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Nor RPM, from what I've seen. It's hard to know how many other variables to address, because the text can get thicker than necessary, but I'll add that one because it's true TTBMK and a common thought. Ultimately, though, I can't prove a negative, and things may change or already have changed with new software. At least with a model one can identify a deviation... more easily, anyway.

I hope the info is (still) useful. :)
 
That is brilliant work you've done there.

I've been trying to figure this out myself, but haven't come near to the precise conclusions you've made. I hope you don't mind if I apply your calculations to my cars list spreadsheet?

Also, from what I've been able to determine, torque gained/lost doesn't seem to exactly match power vs kilometers percentage-wise.
 
What do you mean trading has reported to modify maxiumum power?

Does it or doesnt it?

Eg can anyone get a veyron past 1256hp or a X1 past 1556 hp, as they are the maximum figures for a offline online game?

And also there is no need to speculate anymore I can confirm this for you

"*I speculate that there may be another variable which declines at a rate of around 0.000 01 %/km, perhaps from 100 000 km to perhaps 300 000 km, and which is not reset by overhaul."

I have an x1 with 130,000km on it and even after overhaul it only has around 1500hp. not 1556.

So the car has PERMANENTLY dropped in HP and I dont know how to get it back. It seems you need another x1.
 
Awesome work, thank you!

Regarding the "other variable" for long-term loss: From my observations the permanent loss that an engine overhaul cannot repair starts somewhere after 15.000 km, not after 100.000 km.
 
From my observations the permanent loss that an engine overhaul cannot repair starts somewhere after 15.000 km, not after 100.000 km.

I second this. At least as far as my copper X2010 is concerned. I seem to permanently lose one hp after each overhaul since around 15,000 km. I'm at 29,000 km, and I am down to 1549 hp.

However, I think this varies by car because my Corvette ZR-1 RM has 2,800 km on it with no overhauls, and it still has the same 905 hp. I know my X2010 definitely requires overhauls more often than 2,800 km.
 
Kudos to the OP, great research. I'd started testing how many miles one has to rack up to make an overhaul worthwhile but was a little trial and error, as I tried different cars with different mileages. I thought it was a little higher than 1200km though, but happy to be corrected. There is definitely a point where an overhaul boosts the HP though, and it's best to test with a more powerful car, as a lower power car may appear unaffected due to rounding down.

What I would like to also see is a matrix showing the maximum power for each model with oil change and overhauled engine, but I guess breaking in will have an effect too, making it a little tricky. What I do know though is the mygranturismo site is way off the mark with a lot of the power figures (great site in other respects though)

Oh yeah top tip for anyone keeping tabs on their cars with a spreadsheet or similar, record your service history! If you overhaul the engine or restore rigidity it's a good idea to record the mileage at the time =)
 
Good thread, great research & well done, thanks!


👍
 
Excellent info. I was always wondering if a car at high rpm would wear out quicker in this game like in real life but I guess not. So tha means if you just sit in one spot and rev the engine to the max for an hour straight, it probably will do nothing to the oil or the engine. I guess that makes sense because you can be going 200mph and dump it into 1st gear with no damage. You try that in other games and your engine will blow up instantly.
 
Watto: Use it? Certainly. Torque not matching power: wow, needlessly troublesome inconsistency.

xSNAKEx: Trading affecting power: I haven't looked into it and can't detail it, I just heard somewhere about someone doing something like trading to themselves repeatedly and doing an oil change to the benefit of another 5% each time. Permanent power loss: acknowledged.

Z1-AV69: Permanent power loss after 15k: I'll look for it.

RugerGuy: Variable results between models: I have yet to see it myself, and this one is a challenge because it's so time consuming to get data for even one car, but I'll include it as a possible factor.

Tyger: matrix and mygranturismo data: it would be necessary to note version numbers with each datum, though maybe PD has settled down on tweaking things and all-new numbers would be stable.
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Following up re 1.06/1.07, some of my numbers are coming in different now, so what I'm doing – and might advise – is using the general structure of the model to refine what to look for. I am trying to collect fresh data and hopefully more accuracy will be forthcoming, but this description may not be ready for primetime yet.
 
Briefly, what's different is that overhauling doesn't matter before 5 000 km, rather than 1 500 km, and permanent power loss looks to be 1% per 50 000 km, after 15 000 km. I'd prefer to note changes to the description along the way and hope to do so in the future, if needed, but between the update and the refinement of my understanding I'm just revamping the whole thing. I'll copy the old post for reference sake. Also, this description is a little less verified yet than I'd like, but I think it's accurate so I'm posting it.

I've noticed some weirdness with the transition to the update, BTW, perhaps most dramatically exemplified by this curious bug. I took out a Viper SRT10 '03 that I had previously driven prior to the version update. I oiled it and then overhauled it (to isolate the effects), and it showed 520 hp in the rotating garage display. But when I entered a race and re-checked power in tuning, it showed 523! I exited, and it remained 523. I might have doubted my memory, but I had noted down the numbers so I know that hp popped upon entering the race. Obviously, bugs such as this can easily confuse things, especially changes on the order of a fraction of a percent.

I do note the report of different performance by the X1, but I haven't yet seen it myself. However, I haven't yet tested an X1, or the formula cars. I doubt they perform differently, based on how PD has done things in the past, but it's obviously possible.

While making all the suppositions generally may seem generous, the trouble is that everything goes out the window with each new update, and it's much more practical to make judicious suppositions rather than gathering the same data over and over again, unless there's reason to believe that something is different.

Regarding compiling used car lists and power figures, this description means that cars under 5 000 km should probably be used as the benchmarks, although perhaps cars out to 15 000 km could be used if freshly overhauled (or one could calculate the equivalent based on the formula here).

Old post follows.
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The following is based on my observations, all preceding software update 1.06. Obviously, things may be different subsequently. But I'm not sure I have it in me to chase down more data and I figured I'd at least post what I have as then there's a model to work from, and it's likely close in structure if not still accurate. I'd say numbers are probably well within 10% (e.g. "5%" means 4.5%-5.5% or tighter).
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Basics

Maximum power is modified by two independent multipliers: "engine" and "oil".

Apart from treatments like overhaul, changes in maximum power occur linearly at rates of percent of power per kilometer driven, %/km.

It is important to consistently assess power in a reliable spot, such as the rotating display screen in the garage. Numbers in the garage listing may vary. Numbers in dealerships should be regarded as arbitrary by default, as precedented in the franchise.
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Engine

During an initial break-in period from 0 km for new or prize cars, "engine" increases by 0.01 %/km for 300 km for a total of 3% rise, during which the overhaul option is closed. Overhaul then opens, and "engine" plateaus for 1 200 km. "Engine" then drops by 0.000 5 %/km for 10 000 km for a total of 5% loss.

Overhaul resets "engine" to the beginning of the 1 200 km plateau, comparable to 300 km from new.*

A car from the used dealer does not have a break-in period, even if the odometer reads below 300 km, but "engine" is otherwise comparable in value to what it would have been for a new car run for like mileage without overhaul. A used car can be overhauled immediately, but for very low mileage cars at the beginning of the "engine" decline this may not result in any increase in power (beyond the effects on "oil").
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Oil

"Oil" has three stable states, and two decaying states transiting between them. The "neutral" state corresponds to oil that comes direct from the dealer, new or used, and has no multiplying effect on "engine". The "bonus" state corresponds to oil freshly changed or from an overhaul, and amplifies power by 5%. The "bad" state corresponds to oil in a car has been driven sufficiently far with the oil light on, and attenuates power by 5%.

The "bonus" state lasts for 200 km from oil change or overhaul, then "oil" decays at a rate of 0.05 %/km over 100 km to the "neutral" state, for a total change of 5%.

The "neutral" state lasts until 5 000 km from acquisition of oil (oil change, overhaul, or new car), at which point the oil light comes on.

When the oil light comes on, "oil" decays at 0.005 %/km over 1 000 km to the "bad" state, for a total change of 5%.

"Oil" in a car direct from the used dealer is at the end of the "neutral" state, and will immediately begin decaying to "bad".

Oil color changes from light to dark between about 350 - 700 km from fresh, and is uncorrelated with power changes.
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Other factors

*Permanent power loss also apparently occurs. Numbers may be on the order of (0.000 01?) %/km, perhaps from (100 000?) km to perhaps (300 000?) km, and not reset by overhaul.

Trading has been reported to modify maximum power.

Effects have been reported to vary between models.

The auto-save executed on exit from an event may precede the processing of some mileage effects, so that turning off the system without an additional save may result in the loss of some or all of the effects of driving from that event, e.g. the odometer may revert to the reading prior to entry, confusing the effects of driving distance.

Rounding may affect some numbers.

I have not observed that anything other than mileage affects the progress of "engine", including oil or tuning or RPM.

All of these effects are subject to change without warning or notification if the software changes, of course.
 
Well, the kart behaves differently from other cars I've investigated, looking like it doesn't need/allow oil or overhaul. So that puts a big fat lie to my supposition about absolutely all cars functioning the same way. Though, I still suspect that it's only a few particular types that PD has decided to have wear by different rules.
 
Still (and more so I guess) excellent research, and invaluable for testing.

Thanks for updating when the engine overhaul becomes worthwhile, also means I can throw any of my cars under 5,000km around a track without fear of not getting the best out of them (with an oil change, a little running in and warmed tyres of course!)
 
Alright, well I would just like to share that:
I bought 2 option stream z's with around 1500km on each, overhauled one and oil changed the other and both came out with the same BHP, so it seems that the used car dealer has the "neutral" state if you change the oil only, but for how long is a question in itself, whereas with engine overhaul you know that the neutral state will begin.

Also, I would like to know more about the permanent engine horsepower loss.. your math is incorrect if the information xSNAKEx is giving you is correct. Plus, I haven't put nearly that much on my abt audi tt touring car and it has permanent horsepower loss (despite strong efforts to keep the engine in peak condition, oil changing every 100~200km, overhauling every 2500~5000) Maybe it would be a wise idea to open a thread for people to post their car's statistics after losing horsepower. Given that they post after an engine overhaul (and that should be a requirement), it would be easier to come to a conclusion about when exactly the horsepower is lost and why.
 
How come when I bought a Pontiac Sunfire Coupe GXP Concept '02 with 11.2 miles it needed an oil change?

Maybe it was too long in the dealership's backyard and the oil went bad.:sly:

That's just the way it is in the UCD for all cars. I think it's good you have at least some consistency there. (although I can't say I know what the 0km UCD-Veyron's oil is like; not talking about the prize car)
 
I have a question about this then.. if you buy a used car and change the oil.. will it need an overhaul at its 5000 km mark then, or 5000 km from when you bought it? Also, from my experience every single car from the UCD has bad oil.. (even if its 1km on it) only the ones more than 5000km need overhaul, but even then, this thread states that there's no advantage to the overhaul because the horsepower by then will have depreciated by its regular amount it would have if the car had been in it's non-overhauled state (and so only oil change is really necessary, because you will have the regular horsepower decrease from the car being passed 5000km) @_@ I still feel like it has something to do with the cars rpm though, it seems that every rpm distance the car has traveled, it will need overhaul or else require oil after every time it has been driven (even if it says oil is nice golden yellow, you will have more horsepower reduction than normal for driving it) at which point you -need- the overhaul to continue driving it in GT Life / Practice modes, or suffer from poor engine performance.
 
Don' t know if it's been mentioned already: online races (or at least my lounge races) don't add miles to the car. So, since that's all I do I guess I'll never need to change oil or engine ever again. :/
 
I find it very disturbing that the Overhaul doesn't restore an engine back to a brand new state. In the top of the line cars it is ridiculously expensive, and I don't think we should have to be "afraid" to use our cars. It's only a video game... Very annoying, and useless. I see no reason for this from a gameplay standpoint.

And for what it's worth, my Corvette ZR1 has almost 4,000 miles on it and it still restores back to a perfect state with an oil change. I've been watching it closely, as I have been curious to see when I will need to Overhaul.
 
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