BuckeyeDrew

I am going to attempt some DIY maintenance as my car is due for a (8 year)30K service:

Spark Plugs
Coil Packs
Cabin Filter
Air Filter
Fuel Filter
Coolant, Brake, Power Steering, Trans. and diff. fluid change.
(anything I am missing? oil was just done)

My question is do I need to use OEM fluids or would I be ok with quality alternatives?

The car is not tracked.

Coolant - Pentosin
Brake - Pentosin Dot 4 or Super Dot 4
Power Steering - Pentosin CHF 202 (According to ECS this is also OEM)
Trans and Diff - Liqui Moly 75-90 or Motul 75-90

The non-oem fluids are all available at a local supply house so very convenient to me as the local dealer is across town. Not too mention I am sure these fluids are cheaper.

Thanks!

cfjan

For engine oil, I stick w/ Porsche "approved" oil.. (there's a list published by Porsche) But basically just full synthetic that fits within the viscosity range.

For transmission, I use Mobil Delvac.

For brake fluid, I think any compatible fluid will be fine.

Power steering: I just use whatever Suncoast sells.. ha! (I think it is CHF 202, which is compatible w/ the original 11S) I believe the 202 replaced the 11S.

enthusiast

I see no reason to experiment with the gearbox/diff fluid for a stock setup. See my DIY.

The fuel filter change isn't easy. It can be dangerous if one doesn't get the plumbing fittings right as the fuel will leak/spray.

BuckeyeDrew

The oil seems like the easiest to obtain as you can get Mobil 1 at any autoparts store.

I have been reading on the Delvac and it seems like it is more for the track cars? It would sure be a good alternative as it is less than half the cost of PTX and you can get it online.

I had actually read your DIY last week. Great write-up. I just wanted to know if there was an alternative to PTX as it is much harder to get and pricey. The local dealer does sell it by the litre and claims it is now made by shell.

AudiOn19s

Dealvac can be a little notchy when cold but stands up to heat at the track better. For street only car I'd stick with factory fill. Luftechnik (sp?) sells both online for reasonable money

cfjan

Which ever fluid you use, I think it is more important to change them frequently, rather than a specific fluid.. (just my opinion only, of course)

I have no problem with Delvac.. if it is good enough for the Cup car, it is good enough for me.. !

Mikelly

Bingo

When I was tracking my 996TT 20-30 events per year I would change the oil every 6th day and the gear box about every 10-12 day. The brake fluid was an every weekend bleed. Certainly helped the car survive without any issues.

Mike

BuckeyeDrew

Went to Porsche today and picked up Trans/Diff oil. Sold in 1-litre bottles part # 999-917-546-00 and says transaxle 75w-90.

Thanks for the input.

32krazy!

so is the trans and the diff the same fluid? if i drain the diff am i also draining the trans?

Mikelly

Yes. It's a transaxle. All goes in the same place.

Mike

32krazy!

gotcha. thanx mike. may as well do it this weekend while its in the air

Macster

All I can say is to paraphrase what I'm told when I ask about sticking with OE fluids vs. non-OEM fluids: The techs tell me that the scheduled service intervals are based on the testing experience of Porsche running test cars under a variety of conditions and following the same change intervals.

Thus the change intervals given by Porsche are based on the fact that the fluids hold up and hold up well over this time but are only valid if the same fluids that were used to arrive at the intervals are used.

In the case of engine oils the approved oils are all miscible and thus interchangeable and alike enough that one is as good as another. The only real difference is the viscosities the approved oils come in: 0w-40, 5w-40 or 5w-50.

Now I grant you it is unlikely that Porsche tests each approved oil independently, but it does have access to the very detailed MSDS (material safety data sheets which are getting harder to come by for us layman... I wonder why?...) and other necessary info from the oil maker to satisfy itself that the approved oils are essentially the same that are not different in any significant ways.

That is unless you happen to believe that Porsche selects oils based on say throwing darts at a board with oil brands on it.

The tranny/diff fluids, of which there are two, are miscible.

AFIAK, there is one Tip fluid. I have not yet had any reason to look into what fluid or fluids are approved for use in the PDK.

Pentosin? All I can say is the same Pentosin fluid has been in my 02 Boxster's power steering pump since day one and after 11 years and 263K miles the power steering system is still working just fine.

Now because this question of changing this fluid came up not too long ago I asked the techs about changing this fluid and they in turned asked my why? They never see any issues from the power steering system due to fluid. There can be a mechanical failure (not related to the fluid) that results in a low fluid level which ruins the pump.

They also pointed out the difficulty in getting the old fluid out without introducing air pockets in the power steering system. To perform a full drain/refill -- or a partial drain and refill repeated to eventually replace a significant portion of the old fluid with the new fluid -- is a lot of work. Some old fluid is removed. Fresh fluid added. The system is used to cycle the fluid through, then more old fluid (along with a portion of the new fluid now mixed with it) is removed and new fluid added and the process repeated until one is at the point he believes he has replaced the old fluid with new.

(You do realize what the above means? The techs talked me out of a service. I guess their stealer brainwashing is wearing out and they are due shortly to return for more brainwashing...)

The anti-freeze is deemed lifetime though I have elected to change this every 4 to 6 years. I use or have the techs use the factory antifreeze.

There is I read special additives in this to help lube the water pump seal/bearing.

This is important: My info is the water pump can "leak" a bit and still be fine. This means that anti-freeze/coolant will flow past the seal to the outside. The evidence this is happening is visible by a small white stain on the pump housing which is dried coolant residue. There is a callout as to how big this can be and not signal a problem -- the techs would not share this info with me -- but they did share with me there should never be any signs of liquid coolant.

Thus these fluids have in most cases a very obvious role to fill but with not so obvious side roles that are still critical to the overall health of the engine and the car.

I always find it hard to fathom why anyone would want to stray off the reservation with vital fluids using his car as a test platform.

One gambles possibly thousands of dollars in expensive transmission or even engine repair bills to save a few dollars on fluid costs.

There is also the risk of changing the behavior/feel of the manual transmission or Tip transmission and for the worse. Not worth the risk in my opinion.

enthusiast

That is not the correct lubricant. If there is a Porsche AG document that says otherwise I would like to see it.




Macster's remarks are spot on. Like I said why guess on fluids for a stock Porsche.

BuckeyeDrew

Well, I specifically asked the parts guy at Porsche what fluid do I need for trans on 996 gt3 and after checking into their system he said Shell Transaxle 75w-90. It was the only fluid they sell. I hope it is right as I plan to service tomorrow.

Mikelly

Well that Porsche parts guy should be shot. In going on 7 years doing my own service on 996s, I've never had issues getting accurate info from a Porsche dealer's service counter.

Not knowing a thing about Shell Transaxle 75W90, I'd read all the codes on the bottle and make sure they match the requirements in your owner's manual. In the future you really want to follow the advice of rennlisters. If you can't access the proper fluids locally, contact Pelican, Lufteknic or other OEM vender.

Mike