e9stibi

Thanks to GT gears for clarification. I am feeling good with Delvac in Texas, particularly for my DE car.

Matt Lane

For a 993 used in a DE environment, can you opine on a number of track hours where you would recommend a gear oil change, as opposed to time or mileage?

PS - I run Delvac, and currently change once a year at 4K-5K miles of which there are approximately a dozen track days mixed in (figure 80 minutes a day in a typical DE).

Thanks!

Matt

GTgears

You guys are welcome.

One trick that those of you who live in cooler climates and run Delvac can use is to add some Redline or Amsoil LSD additive when temps drop late in the year and you start to see a change in how your 1-2 feels in the morning. Just an ounce or so will make a noticeable difference.

Or what some of my DE customers who run their cars year round do is run Delvac in the Summer and PTX in the Winter.

Matt Lane,

I recommend changing your gear oil after every half a dozen DEs. But I also base that on the assumption of closer to 120 minutes on track per day. To be totally honest about it, it's not really any sort of exact science, and your existing service interval is probably fine. I'm just super conservative and if it were my car, I would change it a little more often than you do.

One other thing I will mention is Swepco. You'll see the racers say not to use Swepco in the G50 based gearboxes with Borg Warner synchros. In my experience it is a great oil for street driven cars, and tends to be slippery enough to also help with that 1-2 shift issue. I personally run it in my daily driven Subaru, which has triple ring synchros on several gears,and I also take it to the track maybe twice a year. It is a very good oil for much less than the price of the OEM fill, and IMO is not just for 901 and 915 gearboxes.

Mike J

I agree about the Swepco - I ran it in my Targa for over 40,000 miles (2 changes) with no issues, and the shifting was quite good. I do see the negative talk about using in the G50's, but it seems to work fine. I am not sure how it handles the limited slips some of our cars have, my Targa did not have a LSD.

GTgears

201 is perfectly fine to use with the LSD. The 901 and 915 guys race on it all the time.

Here's the thing with LSDs. Most of the LSD specific oils are formulated for OEM applications and their primary purpose is to make the clutch plates, which are usually sintered in an OEM unit, run more quietly. Basically, the LSD oils or additives are just friction modifiers that make it more slippery. For our race customers, we tell them to avoid LSD gear oils because they make the LSD lock less aggressively. This is one of the reasons you see the race guys run the Delvac. And obviously PTX is LSD compatible since it is the OEM oil on the GT3.

So, in short, whether or not someone with an LSD in their car, be it OEM or an aftermarket unit, wants to run an LSD specific oil is really a personal choice. As with many thing there is probably a trade off there. If you run an oil that isn't LSD specific the LSD may wear a little faster but perform better. Or if you use an LSD oil, the LSD will still work, just not as aggressively.

And that last point is something some of our race customers have played with as well. When they found they had just a little too much lock in the LSD, instead of taking it apart and tuning the stack they put in some LSD additive to make it slip just a little bit more. You can in fact tune LSD performance this way when you are dealing with a racecar.

Ed Hughes

Matt this is great info, especially the explanation of the LSD additive and what it does or can do. Thanks!

Meatball964

For us "non LSD" folks....Mobil Delvac 75W 90 should do the job right ?

BradB

I have a question regarding transmission fluid quantity. I understand that 3.6qts is the recommended full level. I just poured in 4 qts (minus what amount of fluid is stuck to the walls of the plastic hose in my Harbor Freight pump) and it is not flowing back out the hole. I can feel the oil with my finger just at the hole.

The car is on a lift so is reasonable level, with perhaps the back being 'slightly' lower than it would be on the ground. Not much. Didn't know if that made much difference.

Also, I turned the wheels a few times while filling thinking that would pull some oil up on the gears. Not sure it matters.

Is 4 qts OVERFILLED? Should I drain some out?

Mike J

I fill until it coming out the hole, put the plug in, run the transmission using the engine, let it settle, then check again, and that last bit I top up with a large syringe so I do not get the pumped oil splashing against the gear that faces the fill hole and giving a false fill indication (by oil coming out the fill hole).

You cannot overfill these if the car is reasonably level (it does not have to be perfect) and the oil is not pouring out the fill hole.

3.6 litres is pretty close when I fill it, that is 3.8 US quarts, which with stuff in the pump/hose/etc may be were the 0.2 quarts has gone. Sounds like you are pretty close.

I do not rely on the finger to find the level, its too hard to really get it bang on. I rely on oil coming out the fill hole, that is accurate as long as as the oil has settled etc.

Oh, how did you know its EXACTLY 4 quarts you put in?

Cheers,

Mike

BradB

Thanks for the fast response. I sucked a one gallon Delvac jug dry. The pump has residual oil in the lines but no more that a few tablespoons.

I guess I'll go on the assumption that I am close, as you said, and leave it at that. (?) I guess it can't do any harm with such a small discrepancy.

ja78911sc

I use a felt pipe cleaner. I bend it at a 90 degree angle and insert it in the fill hole using it as a dip stick.

Slow Guy

^ this

IXLR8

We're totally over-thinking this.

Car level. Insert 4 US quarts. Oil level happens to be at the bottom of the transmission oil filler plug hole with the fluid slowly dripping out.

1 US gallon = 3.785 liters
1 US quart = 0.946 liter

That extra 0.185 of a liter, if it actually went in, amounts to a whopping 12.5 US tablespoons...nothing to lose sleep over.

e9stibi

+2

BradB

LOL! But we're Rennlisters, we over-think EVERYTHING!