Transmission Oil Leak Solved...

[Dus10R]

When I first bought my '06 Carrera S, I immediately put it in my local INDY shop to have all common maintenance items addressed as at that point I did not have the maintenance records on the car, and the dealer I bought it from was clueless as to it's service history. (I stole it price wise so I wasn't concerned with perfection, side note: I later tracked down the maintenance records to find that the car had been serviced religiously, Thank you Lord)

My INDY shop did an oil change, brake check, brake fluid swap & bleed, clutch fluid swap & bleed, transmission oil drain and fill, and a basic API (as opposed to a PPI). Car was in good shape.

It's a daily driver so after a few days of driving it I start to smell Trans Oil. I look underneath and the whole rear driver side is covered in Trans Oil.

Back to the INDY shop...

They inspect it and can't find anything on the trans itself that is leaking but they say that the axle flange seal is bad and that's where the fluid is coming from... so they change the axle flange seal on the driver side and away I go...

I drive it mildly back and forth to work everyday and no leaks...

Then one day I have to drive a considerable distance on the freeway and so I open it up north of a century or so for awhile (it's Nevada, lots of wide open straights of nothingness for hundreds of miles).

Car drives fine, but when I get home I smell trans oil again. Look underneath and Trans oil all over the driver side bottom again.

Take it back to my INDY shop, they can't locate a leak anywhere on the car.

Hmmm... well that sucks. Now I'm gun shy to drive it over 100 in fear of loosing all of my trans oil.

Well I rarely drive over 100 for extended periods of time like I had on that day so I wasn't too concerned. Continued to drive it to work everyday for months and not a drop of Trans oil.

The one day I take it out and drive it north of 100 for an extended amount of time and guess what... Trans oil smell when I get home. This time not as bad, but still visible fluid on the driver side underneath.

What the heck?!

So when my Indy shop replaced my trans oil they didn't use a factory fill, they filled it with Mobil 1 Delvac. Which was fine during the summer months, but during the winter months, when it was cold in the morning I could barely get the car to shift into 1st and 2nd without having to double clutch. So Summer came and it's been warm again and the shifting is better but after reading about these Aisin Transmissions I decided I needed to change back to the OEM Trans Oil before winter arrives again.

So last night I drained my trans and refilled with factory oil.

One thing I noticed (take note 997 owners) is that the drain plug and fill plug are not the same as the 996 which a bunch of people had told me they were. Both are the same 24mm hex head plug. Another thing to note... the AISIN trans has two fill bolts on the side that are identical. One is located higher up right above the drive shaft and the other is located more to the front of the car, just to the right of the Alternator Cable Box that is bolted to the side of the Trans, way lower down.

I got to thinking... I wonder if my INDY shop filled my trans from the higher up bolt? So I have the factory workshop manual and so I look up Transmission Oil Change and I see that from the factory the trans holds 2.9 liters of oil when the trans is dry... BUT! when doing a change it says it only holds 2.6 liters.

So I dig out my old repair invoice and sure enough they charged me for 0.75 gallons of Delvac which is roughly 2.9 liters of oil.

So I go back out to the car and I empty my drain pan into three 1 liter bottles AND 50% of a gallon milk jug.

Suspicion confirmed... they must of filled my trans from the higher bolt and over filled it. Then during high speed runs the turbulence pushed the excess out the vent.

I figured I'd post this long story up as I assume older 997's will be reaching the transmission oil swap stage in their life and owners will be starting to do this more often now and in the years to come. So if anybody else experience this they can just check to see if their trans is overfilled, by simply pulling the fill bolt out. Some oil should trickle out but not a huge pour.

Hope this helps somebody down the road.... cheers.

[White987S]

Good work. Very smart to use the OEM 75W90 trans fluid. And it's only about $26/quart.

[Dus10R]

$26 a quart? From where? I need the name... I paid $39.95 from Suncoast and they're one of the cheapest (or so I thought)

[White987S]

$26 a quart? From where? I need the name... I paid $39.95 from Suncoast and they're one of the cheapest (or so I thought)

I bought from Sunset 2 years ago. Maybe pricing has gone up that much in 2 years. I buy from Phil Coy. Gret guy & service.

[Mijostyn]

I can see some one doing that. Fortunately an easy fix ;-)

I think we get ripped off for Mobilube PTX. You can use Shell Spirax S5 ATE. Ferrari and Getrag specify it in their transaxles. You have to buy it in drums. It is just a tad thicker than PTX but you would never notice it. I use it in the Winter and Millers Oil EE 75W 90 Nanodrive in the Summer.

Delvac was formulated for Caterpillar heavy equipment. As Dus10R notes it is crap in our transaxles. It has a poor viscosity index and it is way too thick when it is cold. All the other oils are in the middle and are OK in warm weather cars but still a little stiff in 1st and 2nd when cold. Only Mobilube PTX and Shell Spirax S5 ATE will work in these cars below freezing.