Fluid change frequency for tracked car?

[dschultz]

Any recommendations on fluid change intervals for cars seeing track time? I've started doing 1-2 track days per month since November and expect that to continue.

Engine oil: I know people have vastly different opinions on how often oil should be changed even without track time but would like to hear opinions, preferably informed ones. I'm running OEM Castrol. Blackstone report in Jan came back clean.

Brake fluid: I've heard flush after every track weekend, after every N track weekends, and just bleed and top up. I'm currently running GS610 at the recommendation of my mechanic.

What about transmission oil? Diff? Coolant?

[pal]

I change my engine oil every 3-4 track days.

Brake fluid- every 4-6 track days since I switched to StopTech BBKs at all 4 corners a few years ago. I use Brembo LCF 600+ fluid.

Coolant- every 40K miles with OE coolant.

Rear diff fluid- every 20K miles with OE SAF-XJ fluid.

Trans fluid- every 40K miles with OE fluid.

My car has about 85K miles on it now.

[TexasZed4MC]

Good guidlines from above.
BUT:
BMWCCA has a tech form that requires a long list to be checked by a shop before the car can be allowed on the track.
Brake fluid must be FLUSHED within 6 months of the existing event.
Also recommend a fluid with a higher boiling point than stock fluid

[jmillet]

I do at least ten HPDS events a year.
I change oil every 4000 miles or less with either TWS, or Red Line 10W-60, or GReedy 10W-60.
I do a brake fluid flush with Ate Typ 200 before the track season.
I change out the diff and tranny fluids every other year with Red Line 80W140 GL-5 Gear Oil in the diff and 50/50 Red Line MTL and MT-90 in the tranny.
My most recent oil analysis at 46,000 miles shows elevated lead at 21 ppm. Looks like bearing replacement time soon

[Small Yellow]

I do probably 15-20 track days a year. This is what I use and when I service my car. Oh and i drive hard every session all session and i tend to drift purposely for at least one session after the day warms up. Cool downs laps are followed religiously afterwards.

Engine Oil
Liquimoly 10w60 (going to start using Motul equivalent 15w50??)
3,000 miles, 3 track days, or 6 months

Transmission Fluid
Motul Gear 300 75w90
Every 3 engine oil change, gear grind, when it feels weird, or six months

Differential Fluid
Motul Competition Gear 75w140
Every 3 engine oil change, when it feels weird, or six months

Brake Fluid
Motul 600 / Project Mu 335 G Four / Torque RT700 (In order of needing to bleed the most frequently on the left to the least frequently on the right per track days)
Every engine oil change, when they feel weird, or six months

Coolant
Redline Water Wetter (Going to try Motul Mocool next)
Once a year

I may be over doing it but it gives me a peace of mind.

[Finnegan]

Originally Posted by TexasZed4MC

Good guidlines from above.
BUT:
BMWCCA has a tech form that requires a long list to be checked by a shop before the car can be allowed on the track.
Brake fluid must be FLUSHED within 6 months of the existing event.
Also recommend a fluid with a higher boiling point than stock fluid

Most of us wouldn't be comfortable with even that CCA time recommendation. I know it's a max recommendation, and I understand why the regulation exists, and it's a good max for general use. I totally agree on a higher boiling point fluid, but IIRC those are more hygroscopic IIRC, yes? And that means 6 months is way too long for those fluids.

Every track day is probably more like it for most folks. It's just a pre-track day prep thing for me. Overdoing it? Perhaps, but I'd rather not worry about that at the end of a straight after being out in a session for 20 min.

Originally Posted by Small Yellow

I may be over doing it but it gives me a peace of mind.

Last thing you want to be thinking about or even have cross your mind while driving are fluid related questions. If it gives you peace of mind and you stay focused on driving, then it's not overdoing it.

[Small Yellow]

Originally Posted by Finnegan

Most of us wouldn't be comfortable with even that CCA time recommendation. I know it's a max recommendation, and I understand why the regulation exists, and it's a good max for general use. I totally agree on a higher boiling point fluid, but IIRC those are more hygroscopic IIRC, yes? And that means 6 months is way too long for those fluids.

Every track day is probably more like it for most folks. It's just a pre-track day prep thing for me. Overdoing it? Perhaps, but I'd rather not worry about that at the end of a straight after being out in a session for 20 min.

Last thing you want to be thinking about or even have cross your mind while driving are fluid related questions. If it gives you peace of mind and you stay focused on driving, then it's not overdoing it.

Good point haha

[dschultz]

Thanks all.

WRT brake fluid, is the main issue water absorption or does the extra heat that tracked brakes see actually break down the fluid in some way? Here are a couple of interesting links I found:

http://www.lelandwest.com/brake-flui...ison-chart.cfm
http://www.stoptech.com/technical-su...rs/brake-fluid

I couldn't find any detailed data on how fast brake fluid actually absorbs water, and how the bp changes as water content changes but here's a very rough "back of the envelope" estimate:

The "wet" in wet boiling pt is measured at 3.7% H20. If we assume this number is based on fluid being in a car for a year, and assume that the change in boiling pt is linear (which it isn't, at least not for DOT4) then the boiling pt of fluid like Castrol SRF is dropping by about 6 deg per month while ATE Type200/Blue drops by about 12 deg/month and the GS610 I'm running drops by about 16 deg/month. Something to keep in mind if you leave the fluid in the car for 3 months between track sessions.

With the exception of Castrol SRF, the "racing" brake fluids with crazy high boiling pts tend to all have average wet bp. So clearly these need to be changed frequently to take advantage of the high dry bp.

My take away is that ATE Typ 200/Blue (which I had been running for years) has only a middling dry bp. If you're melting your brakes, go with Torque RT700, but make sure it's fresh. There are lots of fluids under $20 with dry bp around 600 deg. I don't really see the point in spending $50 or $60/L for something like Castrol SRF if you're just going to flush it before every track event.

Castrol SRF does stand out as having the highest wet boiling pt by a long shot (518) and a very good dry boiling pt (590). So it would seem Castrol SRF is a good choice if you want to leave it in the car longer. But at $60/L you'd have to leave it in 4 times as long to see a cost benefit over something like Motul RBF 600 $15/L.

Just my 2 cents...

[Finnegan]

Best two pennies I've seen in some time!

Thanks.