Flush before adding Swepco 201?

[OZCarrera3]

I'm about to switch over to Swepco 201 from my existing semi-synthetic (GL5) gearbox oil. I've had advice that I need to flush the existing semi-synthetic oil out with a cheap mineral based oil, as the 201 does not "play well" with the semi-synthetic oil.

Being a tight-a** (and also being aware of wasting resources), I'm not keen on spending a minimum or $35-$40 on the wasting the cheap oil, unless it is absolutely necessary. My plan is to take the car for a run to heat up the box, then drain the oil and leave it over-night so that as much as possible will be drained from the box.

Will this be sufficient? Surely the limited amount left in the box (couldn't be more than 5%) wouldn't be enough to impact the effectiveness of the Swepco oil?

[Fishcop]

Sheldon, I used really cheap ($12) mineral engine oil from Supacheap to do the flush and drove around the block to flush it through the box. You'll be surprised at how much oil the box retains.

Have fun!

[porsche930dude]

i wouldnt worry too much about it. It may not mix with well with the swepco but its still oil and it still lubricates as it should. i think your plan of action should do just fine

[dvkk]

Does your Swepco oil say "do not mix with other oils" or something like that? Does it instruct you to flush out the old oil?

To get as much oil to drain as possible, you can jack the front of the car up as high as your jack can go. That will get any traces of oil that remain in the gear chamber to flow towards the diff where the drain is. Turning the engine over while in top gear ¼ turn will also let any oil in the diff drain out.