Everything you always wanted to know about HP, break in, and oil changes

The HP modifiers are:
-5.0% = dirty oil
-3.0% = not broken in
-2.0% = old engine

So, when you get a car, it has a -5% dirty oil modifier and a -3% not broken in modifier. These are compounded, not added. The final number is calculated as:
(base HP) / 1.03 / 1.05

A small problem is that base HP isn't an integer. What you see displayed is rounded off, so it's hard to tell what the exact HP is. You also have to remember that the numbers the car dealer shows are often wrong and you have to buy it and check your garage to make sure. For example:

Mazda MX-5 Miata LS: 168.3 base HP (listed as 157 in dealer)
168 HP broken in with oil change
163 HP new with oil change (168.3 / 1.03 = 163.4)
160 HP broken in with dirty oil (168.3 / 1.05 = 160.3)
156 HP new with dirty oil (168.3 / 1.03 / 1.05 = 155.6)

F094/S: 829.1 base HP
829 HP broken in with oil change (peak)
813 HP with old engine & clean oil (829.1 / 1.02 = 812.8)
790 HP broken in with dirty oil (829.1 / 1.05 = 789.6)
774 HP



After finding a good thread on GranTurmo.com, I think I've figured out how milage works. Apparently GT3 uses km * 0.630 to determine miles (which is a bit inaccurate, but oh well).

oil mileage:
0 - 200km (126mi): no modifier for dirty oil
300km (189mi): oil light comes on, -5.0% dirty oil modifier

The presumable HP modifier % for oil milage between 200km - 300km is:
(km - 200) * 0.05
or
(mi / 0.630 - 200) * 0.05

break in (purchased cars only):
300km (189mi)

The presumable HP modifier % for car milage between 0km - 300km is:
km * 0.01
or
mi / 0.630 * 0.01

old engine (purchased cars):
0 - 800km (504mi): no modifier
900km (567mi): -2.0% old engine modifier

old engine (prize cars):
0 - 500km (315mi): no modifier
600km (378mi): -2.0% old engine modifier

The presumable HP modifier % for car milage between 800km - 900km is:
(km - 800) * 0.02
(km - 500) * 0.02 for prize cars
or
(mi / 0.630 - 800) * 0.02
(mi / 0.630 - 500) * 0.02 for prize cars



So, let's say you entered Formula GT with a brand new F094/S or F094/H (same HP) with an oil change.

Race 1: Midfield, 0mi elapsed, 829 HP
Race 2: Seattle, 67mi elapsed, 829 HP
Race 3: Grand Valley, 163mi elapsed, partially dirty oil, 805 HP (829.1 / 1.0294 = 805.4)
Race 4: Super Speedway, 247mi elapsed, dirty oil, 790 HP (829.1 / 1.05 = 789.6)
Race 5: Rome, 322mi elapsed, aging engine, dirty oil, 788 HP (829.1 / 1.0022 / 1.05 = 787.9)
Race 6: Test Course, 391mi elapsed, old engine, dirty oil, 774 HP (829.1 / 1.02 / 1.05 = 774.1)
Race 7: Laguna Seca, 552mi elapsed, 774 HP
Race 8: Apricot Hill, 627mi elapsed, 774 HP
Race 9: Tokyo Rt. 246, 691mi elapsed, 774 HP
Race 10: Monaco, 771mi elapsed, 774 HP
final: 934mi elapsed (946 actual with pit stops), 774 HP
change oil: old engine, clean oil, 813 HP (829.1 / 1.02 = 812.8)

The important figures here are the partially dirty oil formula for Race 3:
(163mi / 0.630 - 200) * 0.05 = 2.94%
and the aging engine formula for Race 5:
(322mi / 0.630 - 500) * 0.02 = 0.22%

As you can see, these numbers match exactly the per-race figures reported in Der Alta's Compendium

Good stuff. What would be nice is if we can graph this and see if we can come up with a formula. I'm not volunteering though as of yet.
kideng

What kind of formula do you mean?

Wow, nice find. Looks like I know how to take care of my cars now

The drop in power as a function of mileage.
kideng

That formula's in there, along with a huge example. Maybe I just have no idea what you're talking about.

Very nice! This is definitely going in the "Look here before you ask!" thread.

So this formula is only effective until your car is broken in, or does your HP gradually depreciate over time?

The different formulas are effective at different times.

All cars are affected by dirty oil. When you change your oil, it is fresh for 200km (126mi). After that, your car loses power over the next 100km. Then, at 300km (189mi) the oil light comes on and you have a -5% HP penalty for dirty oil. The penalty never goes above -5%. Even if you never change your oil, the car will not be damaged, it will just have this penalty until you change the oil. As soon as you change your oil, you're good again for another 200km.

When you buy or win a car, it has dirty oil (even though it looks clean at GT Auto), and therefore has the 5% penalty.

Now, let's assume you change your oil every 200km, so that dirty oil is never an issue. There's still the break in and old engine modifier. Here's how it goes:

Purchased cars
When you buy a car at the dealer, it has a 3% HP penalty for not being broken in. As you drive it, this penalty goes down gradually over the first 300km (189mi). After you have driven 300km, your car is at its peak HP. It remains at its peak HP until you have driven another 500km (800km total). After you have gone 800km (504mi), your car loses power over the next 100km. Once you reach 900km (567mi), your car has the full 2% old engine penalty. This penalty never goes away or changes. If you run your car at redline for 1,000,000 miles, you will still just have a 2% old engine penalty.

Prize cars
When you win a car (from a race, license gold, or anything besides buying it at the dealer), it is already broken in. It functions exactly the same as a purchased car that already has 300km on it. Your car is at peak HP and will remain that way until you reach 500km (315mi). After you have gone 500km, your car loses power over the next 100km. Once you reach 600km (378mi), your car has the 2% old engine penalty.

I think I'm understanding the point of the oil changes now: To keep you playing the game forever, or to make the AI close when you've beat them in the first 5 races.

Hopefully this madness will get resolved in GT4. It's one thing to get lazy about oil changes, that's acceptable, and actually a good idea. But cars needn't lose power because the game forces you to carry on.

I understand it now. Only bad thing is if you run your car to the oil light, and then oil change (repeat 20 times), your car's HP gradually goes down.

Actually, yep, it's there. :P
Just to add. According to an old post at the ign.com forums, performing the port polish or engine balancing also also "resets" the age of the engine.
kideng

Quote:

Originally posted by pupik
...cars needn't lose power because the game forces you to carry on.

I suppose it is a little silly... Looking at the Formula GT example, you're going half way around the world three times... from Seattle to Rome -- "No time to change the oil, we gotta race!" -- back to California for Laguna Seca. Can you change the oil? "I'd love to but there's no time, gotta get to Tokyo!" All the way back over to Monaco, and still no time to change oil or wipe the bugs off!

But to a set limit - it doesn't dwindle away to nothingness...

Quote:

Originally posted by BadBatsuMaru
I suppose it is a little silly... Looking at the Formula GT example, you're going half way around the world three times... from Seattle to Rome -- "No time to change the oil, we gotta race!" -- back to California for Laguna Seca. Can you change the oil? "I'd love to but there's no time, gotta get to Tokyo!" All the way back over to Monaco, and still no time to change oil or wipe the bugs off!

Although in all fairness, all the races AND travel take place in 1 game day. You're not going to have much time to change the oil in all that...

Quote:

Originally posted by kideng
According to an old post at the ign.com forums, performing the port polish or engine balancing also also "resets" the age of the engine.
kideng

That's pretty nice, and it kinda makes sense. Too bad you can't rebuild the engine on cars where those mods aren't available. It's only 2%, but it'd still be nice for the perfectionist to have the option to rebuild an engine for 20,000cr.

Nice compilation there, I guess this will help to understand all this break in and oil stuff now...

Man, I feel dumb, that just confused me. I should look closer, I guess. I'd rather they just dump the oil change stuff.

ok,i dont get it,im lost but

I don't mind the oil change stuff, except that you should be able to change oil btw races in a race series. I hate how the oil light comes on by the third race or in the middle of an enduro. I think they should refine the oil change system for GT4, not necessarily do away with it. I also think there should be a gas equation. You should definitely have to pit for gas in the enduros.