There are a lot of threads and opinions regarding when to change the fluids in our wonderful cars. I've seen comments like: can't hurt, stuff looks dirty, etc.

My question is this, for daily driving, no track: Are there any fluids where there is general consensus that require more frequent changes than what the owners manual says? Then if so, why doesn't the owners manual say so?

 

Just follow the manual.... I've been driving Corvettes almost 31 years and more than 900,000 miles.... these are just cars, not some rare creation...

 

If you follow the recommended service intervals in the back of your Owner's Manual and use GM's recommended fluids your vehicle will live a long life.

 

For casual non-track driving, the fluid change intervals listed in your owner's manual will be ample and then some.

 

But if you're going to be tracking the car or something else that abuses the brakes, more frequent brake fluid changes are important.
The racing preparation section of the manual will keep you safe with their brake fluid specs and intervals, but you'll be spending a lot of time and money on fluid changes.
I do autocross and an occasional track day, my procedure is to flush in DOT4 fluid once a year, that has worked fine for me.
Others will chime in here with what works for them.

 

The only part of the sched in the OM I disagree with is M7 clutch fluid. Maybe when its filthy dark after one year is OK, but that doesnt sit right with me.

 

I follow the severe maintenance schedule in the manual. The normal doesn't even show a change interval for the transmission fluid.

 

You're one of a kind. Everybody else's manual says different.

 

 

I was referring to the "normal" schedule as not showing fluid maintenance for the transmission. Not the "severe" schedule that I follow. If look at the manual there are two schedules. Normal and severe.

 

I would still change the transmission oil at 45K mile intervals. The new Mobil 1 synthetic oil that was specifically developed recently for this transmission indicated the oil is "less" hydroscopic then the previous Dextron fluid it replaces. Hydroscopic fluids need to be replaced periodically. The A8 transmission is vented so moisture can and does condense within the transmission. You replace your brake fluid don't you? Upshot - transmission oil needs to be serviced.

 

Yes. I can't imagine why they left it off the normal schedule.

 

I agree - the recommended intervals in the owner's manual should be fine for a car that is just street driven.

 

Why is there no mileage indicated for when changing the clutch fluid (manual transmission cars)? On a street-driven car that is never tracked, wouldn't it be done whenever you needed to change out the brake fluid? I am not even sure about what my M7 has in the clutch reservoir, but my Nissan I used to own had a hydraulic clutch and called for brake fluid in its resevoir.

In the "old school" cars, clutches were dry and did not even use fluid. I suspect that most manual gearboxes still use the very thick "gear oil" and it doesn't go bad as quickly as automatic transmission fluid.

Lots of good information here!!

 

JK - The M7 uses Dot 4 brake fluid. Its a bit of a job to fully bleed the system as the drain is blocked by the exhaust. Many of us here use the Ranger Method. Its not perfect but better than nothing.

 

I would recommend doing this as I did it on mine and the fluid was filthy, also clutch performance improved (smoother release).

 

I would do the brake and clutch fluid every 2 to 3 years just to be safe. The 2019 manual lists every 3 years and most other OEMs have similar time frames.

For reasons unknown the manual for my 2014 says brake fluid every 10 years which is crazy. Back then they recommended DOT3 which lasts longer then DOT4 but not that long! The clutch is listed as every 30k under severe use. I do the clutch fluid every other oil change using the ranger method as its super easy.

 

I assume that the "Ranger Method" involves a turkey baster or some other small suction device where you siphon out all the fluid possible from the reservoir on several occasions.

I suppose you keep doing it until it looks clean - similar to doing it with the brake fluid. Sounds logical, I suppose.

My 2017 Stingray [7M, non-Z51] will be four years old in February of 2021. I have just 13,500 miles on it so far. It is always garaged and never tracked or even driven hard. I have already changed the oil & filter four times (Mobil-1, of course) and will do it once more before winter arrives.

I am thinking of replacing the clutch & brake fluid in March when my state inspector is due......although my brake fluid looked clean the last time I checked it.

Thank you for the comments! Very informative people here.

 

^^^
Yes you got it RE: Ranger Method. Do it for the clutch fluid, Dont do it for brakes. You dont want air in the system. Brake bleeding is a relatively easy process to do it right.

 

The OM provides a guide on which vehicles should have the Normal Service Vs the Severe Service.

Because of the way people use vehicles, maintenance needs vary. There may need to be more frequent checks and services.
The Additional Required Services - Normal are for vehicles that:
. Carry passengers and cargo within recommended limits on the Tire and Loading Information label. See Vehicle Load Limits on page 9-14.
. Are driven on reasonable road surfaces within legal driving limits.
. Use the recommended fuel. See Fuel on page 9-53.

Refer to the information in the Maintenance Schedule Additional Required Services - Normal chart.

The Additional Required Services - Severe are for vehicles that are:
. Mainly driven in heavy city traffic in hot weather.
. Mainly driven in hilly or mountainous terrain.
. Frequently towing a trailer.
. Used for high speed or competitive driving.
. Used for taxi, police, or delivery service.

Refer to the information in the Maintenance Schedule Additional Required Services - Severe chart.

I would put Low Mille garage queens in the Severe Service Schedule as well since letting a vehicle sit for long periods of time is one of the hardest things you can do to it. Automotive designers do not design their vehicles to sit around. That means they need to operate.

Bill