DDK - Die Deutschen Klassiker

I’m thinking of doing a gearbox oil change in my 912 (902/16 box) and just wondering which oil people use/recommend.

I’ve heard several recommendations over the years for swepco, I’ve also heard plenty of people say this is recommended if you have worn synchros as it can extend their life, but I’ve also heard some reports from people saying their gear change was more difficult after changing to swepco, not a road I really want to go down as it currently changes beautifully.

Think I’d rather go with something as close to oem specs as possible ideally, is there anything additional to be concerned with like the equivalent zddp issue with engine oils?

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I always used a good quality hypoid EP90 gear oil - usually bought from Eurocar Parts or GSF ...

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I don't know if it's the best but I rate all oil by Smith and Allan

https://www.ebay.co.uk/itm/Fully-Synthe ... 890.l49286

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I agree with Andy

A decent EP90 dino oil is what was specified by Porsche.
If it ain’t broke.......

I put the swepco stuff in mine as I read it was better for older gearboxes and it seems to work really well. But I wouldn't say it made a huge difference in shifting gears.

Cheers all, appreciate the recommendations

Just about to order some gearbox oil but so confused as to whether to stick with GL4 or go for GL5 spec?

From what I've read GL5 gives far better lubrication than GL4 but the additional additives can accelerate synchro wear, not something I'm keen to actuate.

I've seen some comments about some GL5 oils being OK to use and others not. Am I best steering clear and just sticking to GL4? If so will that give sufficient protection?

So at the moment I'm looking at the following options from Opie:

Millers who seem to offer GL4 and GL5 in their classic range, both apparently fine for use with yellow metals, are there any yellow metals inside a 901 gearbox and is it only the yellow metals I need to worry about with GL5?

https://www.opieoils.co.uk/p-68916-mill ... ntID=89758

https://www.opieoils.co.uk/p-69297-mill ... ntID=91296

Motul which states that it meets GL4 and GL5 specification. Apparently uses molybdenum bisulphide to reduce noise, isn't this the same additive used in Swepco 201 that a lot of people seem to dislike these days?

https://www.opieoils.co.uk/p-60207-motu ... ntID=67555

Or Castrol, which meets GL4 spec

https://www.opieoils.co.uk/p-77274-cast ... tID=112022

Utter minefield!