Oh, well, oil...!
Always work the oil.
It may alter the horsepower but it is actually just part of the breaking in process.
When I setup weekly races I never use a sim car without allowing oil changes.
Regarding the brit thing...
That's cool... actually, it's the same thing I did.
I would stick to it, makes things a little funner.
There is one more thing I want to stress...
If you're new enough to be asking questions about how to win races or what to do it with, then check this out...
https://www.gtplanet.net/forum/forumdisplay.php?f=116
That link should lead you to the OLR school (thank boombexus).
That is the place to get a start on how to really tune your suspension as well as all sorts of other elements regarding racing in this game.
Setting up your suspension properly is gonna be key to running races the way you're talking about.
I'm not trying to say you don't know what you're doing or anything like that... I have no clue what you do or don't know...
What I'm saying is that there are tricks to setting up suspensions and often times those "tricks" can make a 1 or 2 second difference in an individual lap scenerio.
Take that into account when you're running a 10 lap race and all the sudden as little as .5 seconds faster per a lap can be a major difference.
Like I said before, good luck and keep us informed.
oh yeah...
Welcome to the gtp!
Forgot this too...
https://www.gtplanet.net/forum/showthread.php?t=43609
Should lead to "m-spec's tuning guide"
Good stuff! 👍