I have searched and could not find any relevant information. How often to you guys change your drivetrain fluids after a day at the road course. I usually change all fluids (oil, tranny, tcase and rear diff) at 5000 miles. I have done two HPDE track days but only have 1500 miles on the fluids now. Can I wait until the 5000 miles or should I change them now?

I use amsoil MTG for the tranny, mobil 1 for the engine and diaqueen for the tcase for the rear diff.

 

I change my motor oil before and after a weekend... I then change all my driveline fluids after (2) track weekends... I also bleed my brake fluid before an event regardless of use...

call it what you will, but I like my oil fresh...

 

Probably a bit overkill on the engine side, I do 3k miles or 5-6 track days, whichever comes first myself. Oil is always going to quickly turn black after running it hard, but if it doesn't get over temp it should still be doing it's job properly. Topping fluids off every day to make sure they are the proper level is a good idea regardless. For brakes I also try to stay on the bleed before every event be it 1 or 2 days since moisture can absorb into the system over time. Honestly the driveline fluids should be fine on a 15k maintenance schedule, replacing them earlier seems exessive if you are using the good stuff but checking that the levels are ok can't hurt.

 

I change my oil and bleed my brakes before every track event, regardless of the miles on the car and I change the driveline and brake fluids every year (5-6 track days & ~3000 miles).

 

It really depends how hard you're pushing the car and what fluids you are using. As a rough guide for HPDE levels; at least cut your maintenance intervals in 1/2!

If you're using that Mobil 1 stuff; you should change it as often as you can! If you're running something quaility like AMSOIL then you have a ton more protection. If you want some detailed track info, check out these review threads:
https://www.evolutionm.net/forums/se...-929s-evo.html
https://www.evolutionm.net/forums/se...ck-review.html

Same goes for brakefluid. With quality stuff like AMSOIL or Castrol SRF that protects to 600+ degrees, you don't even need to bleed between events (assuming you have good braking habits).

To give you an idea, here's what I do now that it's mainly a track-only car, and I have about 55 track days on the car to this point. I know the guys that race SCCA T2 / NASA ST2 flush the engine oil & trans oil after each race weekend!

• Engine oil - every 2 weekends usually; or after 3 hard days / 250 track-only miles
• Brake Fluid - Full flush yearly; bleed only when I change pads!
• Trans/Diff/ACD - twice a year

 

oil every track weekend, maybe stretch it to 3 days if it was rainy, etc.

tranny/trans/rear end every 10 events...

Coolant, well, anytime you need to work on the turbo. (ran 80water/20 coolant).

brake fluid? bleed before every event, if you mushed it good the past time, then a full flush, if not, and event was less than a month ago, a simple bleed will normally suffice. (motul 600 fluid)

 

Given the amount of fuel that the Evo's typically inject, a good portion of that fuel ends up in your oil pan. Meaning that you're fouling your oil with fuel before it breaks down. Why pay tons of money for AMSoil or Redline synthetic oils when you won't be able to use their extended drain intervals anyway?

Buy Mobil1 from K-mart for cheap and change it every session.

How I decide how often I should change my fluid. I weigh what happens if the fluid fails what it was designed to do and the consequences.

Usually the failure results in death or engine/drivetrain failures....which end up costing money. Then I weigh the price of a new engine vs. say 4.5 quarts of Mobil1. I do my best not make 4k dollar mistakes that could've been prevented by a 30 dollar service item.

 

I go a few (3-4) events between changing oil. Never had an issue in any of my track cars. Mobil 1. Synthetic oil is really amazing stuff, and you don't really need to change after every event.

At 10K miles, I changed all of my driveline fluids: TC-SST transmission, transfer case, diff.