I'm going to change the fluid in my Boxster S 6 speed - do it twice?
 

My 2002 Boxster S has what I believe to be the original load of gear oil in the trans. It's got 106,000 miles on it and it doesn't shift as smooth as I think it should. I bought the expensive Porsche lubricant for it.

However, before I use that, I was considering running some Mobil 1 synthetic in the gearbox for a thousand miles or so sort of as a flush. I'd drain the old junk out, fill with Mobil 1 then drain that after 1000 miles, to get all remains of the old stuff out with it, then fill with the Porsche fluid. I know that can't hurt things but am I wasting my time and money doing that?

Yes, you would be wasting time and money.

Not sure but Mobil 1 is an engine oil not gearbox over here in NZ. Quite a different product. Been driving manual cars for 40 years. Never ever changed the gearbox oil in any car or ever had a gearbox or diff problem.

PS From a bearing manufacturer, if a bearing has completely clean grease, it would last for ever. Wearing comes from contaminates. Gearboxes and diffs are sealed and should therefore stay clean.

Engines are quite different. Lots of dirt from the incoming air and combustion by products, hence the need to change.

The stiffness is some other issue.

Just did mine, probably 17 years old but fewer miles. Used standard Porsche gear oil. Noticeable improvement within 20-25 miles.

When I changed the rear diff oil and the transfer case oil in my Toyota FJ Cruiser, I picked up about 1 MPG highway, which was a nice bonus and fairly significant, since I went from 16-17 MPG to 17-18 MPG.

I bet you will see an improvement.

I was wondering the same thing, since at my next change I am going to Millers CRX 75w90 NT, and I would like to flush out all the current oil, but that will probably be impossible. What I will probably do is take it for a little drive and get it nice and warmed up, and then get it home and jack it up and start draining the old oil while it is still warm. Maybe that will help more of it drain out, and that is probably as good as I'm going to be able to get it...

Thanks all. I guess I'll just get the gear oil hot by driving, then drain it and put in the Porsche oil, and hope for the best.

I filled mine with Fuchs Titan Race Synchro 75w-90 and it’s improved the shifting. When cold it’s a bit sluggish but when hot I find it much improved over whatever was in there when I bought it.

Been great on track also.

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It will be teeh best thing you do. Remember, remove the fill plug before you remove tee drain plug just in case teh fill plug is seized which has happened.

Detailed thread here on me changing mine. Might help or might not???

http://forum.porsche-club-ireland.com/index.php?topic=8069.0



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I like to pull the drain plug as soon as I return from a drive and let it drip overnight. The next day put the plug back in and refill.

You will find, unless your trans is cooked, your new oil will be fine. No need for any funky flushes or whatever. Things that can effect shifting are the shifter itself, very worn out if original. Motor mounts, same as shifter. Possible shift cables and linkage. Porsche trannies are notchy, they always have been. They are not designed to blast through the gears. If you are experiencing balk, or second gear pop, you have other issues that fluid my help initially but will need to be addressed at some point.

Keep in mind too that you need to remove the lower pan to get to the drain plug. The crossmember bolts can a be a bugger to get lined back up. A lift is VERY helpful when messing with that sucker.

check this thread . . . .

http://986forum.com/forums/diy-project-guides/62465-transmission-gear-oil-change-made-easy.html

just totally wrong

Haha, I know, right? I didn't even know where to start with that.

"Sealed for life", as it relates to drivetrain components, is self- fulfilling, Haha. NEVER, EVER trust that.

Lubricants are broken down over time by much more than simple contaminants. Shear forces are primary, as are heat and moisture.

Add to this; every single time that I have changed fluid in an otherwise "sealed for Life" component, I have discovered that the fill level is significantly lower than the factory recommendation. This must be due to fluid going somewhere. Regardless of the absence of visible leaks, weeps, or seeps.

Seriously: never trust old lubricant. Never, ever.

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Any part that has "life" or "lifetime" (as relating to useful functionality or warranty) always makes me chuckle....if the part has failed, didn't reach the end of its life? If it's labeled "sealed for life", that just means (to me at least) that it's something that I can't service...or at least not without some creativity and a big hammer..."life" does not quantify some amount of time, could be 10 years or 10 minutes; it most certainly doesn't mean forever.