How often to replace transmission fluid?

rickdm · 02-20-2005, 06:57 AM

I was watching one of the Best Motoring Videos the other day (this is a Japanese series that you can find on DVD). I love to watch the 'foot' cameras as these guys heel and toe. They had the head of Spoon Racing, one of the top Honda tuners in Japan, and they were asking him about frequency of oil changes after track use. He felt that the transmission oil was under more stress than the motor oil (no circulation, no pump, no filter), and that he changed his transmission fluid every time he changed the motor oil. Usually after every track session. This seems like a lot, but than again most people wear out synchros and other transmission parts sooner than they do engine parts. Dos this level of maintenace make sense? Or is once a season enough?

rickdm

azasadny · azasadny's Garage

I've changed mine twice since I got the car (6/2002) and I'll probably change it again in the fall of 2005. I only put about 4-5K miles on the car per year. The first time I replaced the fluid with Swepco, the old fluid looked like chocolate milk and stunk. The fluid change really improved the shifting.

jmarenas · jmarenas's Garage

I did my first one right after I purchased car year and a half ago, will do this spring, G-50 and I use Mobil One . Shifted MUCH better after first change, remember OIL is CHEAPER than METAL. Worth the time and dough, I will continue once a year or so, I drive around 5-7k per year.

HarryD · 02-20-2005, 08:53 AM

Quote:

Originally posted by rickdm
I was watching one of the Best Motoring Videos the other day (this is a Japanese series that you can find on DVD). I love to watch the 'foot' cameras as these guys heel and toe. They had the head of Spoon Racing, one of the top Honda tuners in Japan, and they were asking him about frequency of oil changes after track use. He felt that the transmission oil was under more stress than the motor oil (no circulation, no pump, no filter), and that he changed his transmission fluid every time he changed the motor oil. Usually after every track session. This seems like a lot, but than again most people wear out synchros and other transmission parts sooner than they do engine parts. Dos this level of maintenace make sense? Or is once a season enough?

rickdm

Remeber that racers will do things more frequently than us mortals due to the extreme stress they out on their cars and other factors which do not apply to us. You should remember, these folks also replace most rubber lines after every race and remove/adjust most everything weekly.

That said, I think Porsche recommends tranny oil changes every 60,000 miles. That seems a bit long to me. I would do it once every 2 years or 25,000 miles. JMHO.

rickdm · 02-20-2005, 09:47 AM

I figure that I will probably do about five DE's this year, and perhaps a couple of TT's. With eight 25 minute sessions per DE weekend that comes out to 3 hours and 20 minutes of track time. After each DE I was thinking fresh motor oil. If I change the transmission fluid once a year that would be 18 hours and 20 minutes of track time between changes. Too much?

Perhaps I need to start another thread on this, but I would like to know what those of you that track your cars follow as far as maintenance intervals?

Thanks,
rickdm

anthony · 02-20-2005, 10:08 AM

Changing the oil after every DE seems excessive. Is a DE really harder on the oil than driving the car normally? I would just change the oil every six months assuming you aren't putting a lot of miles on the car.

HarryD · 02-20-2005, 10:25 AM

Quote:

Originally posted by rickdm
I figure that I will probably do about five DE's this year, and perhaps a couple of TT's. With eight 25 minute sessions per DE weekend that comes out to 3 hours and 20 minutes of track time. After each DE I was thinking fresh motor oil. If I change the transmission fluid once a year that would be 18 hours and 20 minutes of track time between changes. Too much?

Perhaps I need to start another thread on this, but I would like to know what those of you that track your cars follow as far as maintenance intervals?

Thanks,
rickdm

Seems excessive to me, but I am not a track guy. I would think motor oil chages at 3,000 miles or once a year would be more than adequate unless you are a full race team that tears down the engine after every race.

jpachard · 02-20-2005, 10:46 AM

I change my trans. fluid after every 10hrs. of run time(track). If you figure a good DE you get 2hrs. per day, it goes by quickly.

Cheers, James

randywebb · 02-20-2005, 11:31 AM

I'll be interested to hear what Mike/Lubemaster has to say. Also, Sherwood has posted on this before (or was it Warren?).

Note the following:
- trans. oil is not exposed to super high heat or combustion nasties, like engine oil is.

- PAG has issued TSBs on when to do this + the workshop manual specs. The latter show a big change in intervals for early 911s vs. later ones.

- The type of synchronizer used in the trans. changed and may account for the extension in drain intervals.

- The gear oils we were using in 1971 are not nearly as good as the ones we can buy today.

- Cars that are run only a few miles a year should change the fluids based on time. I use shelf life to get an idea when.

- I discount the Honda "expert's" notions....