When do you replace your transmission fluid?
 

Yeah, when do you replace your transmission fluid? number of miles or months/years?
Thanks.

I do it by miles and not too many...it is heat dependent and I drive year round in southern Az.
Often drive spiritedly in 100 degrees plus and no radiator on my '83 915 tranny. In cooler climes prob not as much an issue.

Per Bentley 15K miles or 2 years.

At the beginning of every track season (spring). I put maybe 1500 miles on it per year. Oil's cheap, as the saying goes...

if you have never done it, it is time.

I've gotten cars with over 100k miles on the original gearbox fluid, and there were zero issues.
Change it, but it's not anything to freak out over. I'd be more worried if it were very low.

I'll probably change mine next year, when I think it it will have had about ~12k miles on it, but I've had Redline synthetic oil in my SE-R's gearbox for at least 60,000 miles and I don't have to even think about it.

:rolleyes: umm, I think I'll do it sometime soon...

Waynes book (Project #36) says every 30,000 miles or 2 years assuming 15k/year. He also says depends on how you drive the car, track vs. Street. I put about 2k on mine per year street only so maybe in 10 years i will change it again. I used Mobil 1 gl-5 synthetic on mine, costs about 10/quart, shifts like buttah now. 89 with G50. Does your trans have lim slip diff? If so get oil with additive.

15k miles? That's 5 or 10 years for me :lol:

Guys,
I drive around 1k to 3k miles a year. Saying 3k is probably a little too exaggerated. I usually change it when I like, some times once per year, some times after 2 or 3 years. Engine oil too, I used to change it 3 times a year. Then I reduced to twice a year. Friends told me that I was wasting oil/fluid, then now I do it once a year. I guess once every 2 or 3 years for transmission fluid is ok huh.
Thanks guys.

Reiver at what level does your oil temp gauge goes up to? 210?240 farenheit?i use mine as a daly driver (82 SC) and the needle goes up to the last withe mark but never more,thanks for the advise

IMO, it depends on what transmission and what lube you are running. With a G50 running synthetic gear lube, you can extend the intervals longer than an earlier car with non-synthetic lube. The Porsche type synchronizers in the 901 and 915 transmissions don't like the slippery synthetic lube, so you have to accept shorter drain intervals with the non-synthetic lube. I have read that the big problem is the action of the differential gears on the oil molecules. The gears sort of chop up the oil molecules after long use. Apparently,synthetic oil withstands this better. So, looking through the records on my 1986 with a 915 that I acquired this year, it looks to be about 15k since the last gear oil change. Time for me to do another one.

I do my 915 oil change every other year. I do drive my car and I have put over 6,000 miles on it this year.

Don't put synthetic in your 915. It's fine for everyone else posting who has a G50...

I change my gear oil every 2-3 years on my street cars. 15k mi on the ones driven a lot. Track cars are a totally different beast.

The best bet is to change it when you want to get away from the nagging wife. This might be daily, or it might be every 10 years. Either way seems to work

So since you are going 100k between changes can we assume she left you?

They are many options:
1) she left
2) she died
3) she never nags and does whatever I say
4) I'm a swinging bachelor
5) I'm gay
6) I'm a swinging gay bachelor
7) ???

My trans starts to shift not so nicely, as with new fluid. I use Swepco 201 and when fresh it shifts like a Swiss piece of machinery, old like a cheap Italian car. The shearing of the oil molecules by the gears causes it to breakdown, add some localized heat and the fluid gives up the ghost.

+1, 915 synchros need help to slow down, synthetic will not allow that. Plus if you have LSD, it growl like a TANK, ask me how I know.