Should I change my transmission oil?
 

I have a 2001 Boxster S with about 130,000 kilometers. Bought it three years ago and I don't know if the the transmission oil has ever been changed. I find shifting quite stiff until the transmission warms up. A sign I need to change the oil? Actually, the shift action is pretty ropey anyway. Probably need new cables?

Hi Peter,

My car isn't that far off from yours in regards to mileage; Age wise, our cars are the same. I'm at 140,000KM and changed the transmission oil last year when doing the IMS, RMS, and all that jazz. Like yourself, I was doubting whether or not the oil was changed, but since the transmission was being dropped, I asked the shop to replace it with original Porsche oil. No issues with stiff shifting whether cold or not. I am happy with the factory oil.

I can't speak for the ropey shifting; Perhaps an adjustment will suffice, but you may want to get an expert opinion on this. I see you are in Toronto - lots of good shops to pick and choose from. If I recall, you went to Porsche Centre Oakville. I normally take my car to the folks at Mantis Sport not far from the dealership. Good luck!

Change the oil, you are way overdue................

Thanks fellas. I will change the trans oil. I noticed someone on the forum used Red Line 57904 (75W90) Synthetic Gear Oil. Thoughts?

None that are any good. Porsche used a full synthetic gear oil that was made to their unique specs in these transmissions. Over the years, I have lost count of how many times we have had cars come in with complaints of transmission noise, poor shifting, etc., all of which went away when we dumped whatever was in the trans and put in the factory oil. Yes, it is pricey, but does an excellent job and is long lived, and does not cause any problems.

Choice is yours..............

JFP - do you know what is the recommendation of Porsche for changing the transmission oil (miles / years) ?

We like to do it every 30-40 K miles. Porsche's mile recommendations are ridiculous.

thanks JFP, what is a reasonable cost for doing that at a mechanic ?

Done by itself, maybe $100; done as part of other service would be less.

@ Peter - I would not recommend Redline. It will only exasperate your symptoms you described. They are good if you are racing/tracking the car, but as a daily driver, Porsche oil is excellent.

Thanks JFP. I hear that comment about Porsche's recommendations quite often

It is not clear when to replace what, except that I saw in many posts to replace the oil every 5k miles.

So, would be very beneficial to 986 owners to have 1 sticky post that will state how often to change all the major items.

What do you think ?

+1 on using the real stuff. I used a generic fluid back on 2015 for what was my cars first change and it was horrible. It was like the synchros didn’t exist. I drained it after a couple of days and put in the Porsche stuff and it is like night and day better. Don’t balk at the price, pay once and get it right.

I think it would precipitate another oil argument...........;)

Realistically, how and how much the vehicle is used plays into this; tracked cars and daily drivers need more attention than weekend toys. That said, in general, I would use the following:

• Coolant every five years, or when is shows signs of degradation (pH, freeze level, etc.)

• Engine oil and filter every 5 K miles
• Manual gear box every 30-40 K miles
• Tip fluid and filter every 40-50 K miles

And remembering to use the correct fluids, such as an engine oil with high film strength and ZDDP levels.

so you could do it for 2 categories / classes - daily used and weekend used.

arguments can be healthy, innovation is derives from that :-)

Gear box oil and coolant suggestions would remain the same. Non weekend toys, I would invest in collecting some UoA's across miles; when the TBN values drop to 50% of that of fresh oil, it is time to change the oil. If you were to compare TBN values across multiple cars, you would find the decline rate would vary dramatically, based upon real world usage. But once the TBN (total base number, or the remaining active additive package in the oil) hits that 50% threshold, it is time to change it based upon your actual usage.

Simple.................

Yes but rarely in oil debates.

Is the best option just to buy the transmission oil from the local Porsche dealer or will one of these do: 999 917 546 00 (Shell) Shell Transaxle (75W-90) or Mobil Mobilube PTX (75W-90)?

pilot4fn - You are lucky being in Finland because you have access to the Mobil transmission oil. This seems to be impossible to get in Canada (or North America, for that matter!) There are a handful of guys here in Toronto on the Rennlist forums who bought a barrel of Mobilube and split the oil among a group of guys for their aircooled transmissions, but as far as I know, none of the watercooled guys bought it for their cars. 90% of them still stick to the Porsche transmission oil as far as statistics go. Given our currency conversion rates against the US Dollar, most of us in Canada just buy the transmission oil from the local Porsche dealer. It isn't super expensive, but also not cheap by any means.

We always purchased ours directly from a dealer, that way there was no mistaking what we were using.

Thanks JFP. I will get the real stuff from by nearby Porsche dealer.