968norway

It has a drilled airbox, but I am using the standard paper air filter, nothing special there.
I know the guy who did the engine work, a very good mechanic, but sometimes not so good at the 'while you're there' type extra work. One possibility is that the valve guides were checked and deemed ok. It turns out there was about 20,000 km left in them, that's what I am hoping.
Aren't the valve guides a weak point in these engines?

PhatPhlatSix

So he expected the engine to be dismantled again in 20,000kms? Obviously didn't have much faith in his own work....

968norway

Is there any way to predict exactly when something will go wrong? If something is within acceptable tolerances, is it unreasonable to not change it?
Since I don't know what the problem is yet, this is still just speculation.

freno a mano

I use 5W40, my oil consumption is less than 0,5L/2000Km

For my next oil change I have bought Castrol Magnatec C3 5W40, suggested on castrol web site for 964s

with 10W60 is the engine more quiet at idle?

ras62

Valve guides are certainly a weak point. Easiest way to check them is to remove the bottom valve covers and check for movement of the valve or you could drop the exhaust manifolds and look to see how much oil is collecting in the exhaust guides. If they have been done recently there should be little to none.

968norway

That's the plan, I have it booked in at the shop next Wednesday and no, not the guy who rebuilt the engine.
I think I am just expressing some frustration with this car. There have been quite a lot of things to deal with that have cost a bit of money, brake calipers, fuel tank, etc. etc. When I bought a car with a rebuilt engine, that was the one thing I thought I could feel ok about.