bhensarl

I'm getting ready to replace my transmission fluid and I was wondering which brands people prefer. I would wager that Mobil 1 would be a solid candidate, but is it really worth the extra money? Also, the manual says that the front axle takes 1.27 qts and the rear takes 4.02 qts. So, to change out the fluid I would require about 6 qts, right? Or is it like motor oil and not all of it will come out? Also, do the front and rear axles fill from the same point?
Power steering fluid: It says in the manual use 1.06 qts ATF Dexron. I looked at a few brands of power steering fluid at the store and in no cases did I see the words "ATF Dexron". What am I looking for exactly? Any suggestions on brands to use?
Thanks

Bill Gregory

For our G50 transmissions, synthetic fluid works well, and Mobil 1 seems to be the fluid of choice, although there are others that would work fine too.

bhensarl

Oh, and how necessary is it to change the fluid? Adrian's book says that it doesn't need to be changed unless it's fouled. How do I know if it's fouled? Is changing the fluid a part of normal preventative maintenance?
Brian

springer3

General Motors transmissions use ATF Dexron, so you should have no trouble finding it. I use Mobile 1 full synthetic. It is expensive, but you use very little, so why not the good stuff?

I have no clue how you tell for sure if the oil is fouled. I guess if you have been under water or travel in a lot of dust, you can assume contaminants are there. I think you can assume some level of contamination over time even in good conditions. Porsche recommends flushing the brake fluid every two years, and that is a closed system except for a small vent. Changing the other fluids every two years is a small increase in the overall maintenance budget, and it is good insurance against loss or contamination.

bhensarl

Springer,
When you say "you use very little", exactly how much is that? I'm assuming it's less than the 6 qts I mentioned in the first post?

springer3

I don't have a C4, but your values look right.

If you change fluids every two years, even 6 quarts is not a big expense. Honestly, I can't even recall how much I spent. Price a transmission rebuild, and it will scare you into shifting gently, and using the best lubricants you can get.

Jay H

I've got a '90 C2 with 32,000 miles. I took it to the dealer last year to have the tranny fluid changed and they (the mechanic and service manager) refused to change it stating that "Porsche recommends changing the tranny fluid only at 60,000 miles". I was given the line of "if it ain't broke, don't fix it". When I bought the car in 2000, my trusted mechanic would not change it then either.

My records on the car show that the fluid has never been changed and since I only put under 1000 miles on the car per year, it might be 28 years yet before the car hits 60,000 miles.

How long can this fluid last and be effective? Any thoughts? It can't be good to have 14 year old fluid in the tranny... (My car has not been tracked other than about 4 autocrosses in it's life.) I'm gonna crawl under the car and do it myself this summer (if it ever warms up around here). Or, should I leave well enough alone...??

Jay
90 964

springer3

Porsche recommendations are sound for normal service - the transmission is heated up every day, and 60,000 miles comes in 4 - 5 years.

For a low-usage car, I would worry about water condensation - fluid chilled on a cold winter night will say cold and collect condensation on a following warm/humid day. My car spends time in the basement, so condensation is a concern.

I changed all fluids shortly after getting the car. The PO had a record that everything had been changed recently, but it did not say with what, and you can't be certain the work was really done. The old oil looked fine, but it is a comfort to know for sure what everything is, and know it is fresh and clean. It is not a pleasant job, but if you are careful to keep the stuff out of your hair, you will finish the job with a good feeling. Go for it!

911kid

My manual says to use Dexron II D for power steering fluid. I tried to find this at the auto parts store and could only find Dexron II E and Dexron III. Checking on the internet it seems like the II E and III designations are compatible with the II D. Probably the II E and III are just newer versions. By the way this disignation is for auto transmission fluid and not power steering fluid.

flatsixcrazy

Hi Dennis,
Have you find the the source for Dexron P.S fluid?. I have not had any luck finding any at local auto part store. Thanks. Andy

911kid

I used Dexron IIE transmission fluid. Any auto parts store will have it.