[DuSh]

Hi everyone,

It may seem I'm posting in the wrong forum, but I think you guys are the one who has knowledge about Valve stem seals issue in n63.
I checked realoem and it looks like n63tu uses same valve stem seals, same design engine basically with crazy hot cats located right in the back of engine slowly frying everything and especially rubber components (seals, gaskets, hoses etc)

I was wondering if you can share some knowledge for us f15 owners of how to avoid expensive repair and maybe any remedy available that you know of?

1. How often this happens, can someone approximately say like in 10% of all 50i engines or more or less? Just to have rough idea

2. Is it true that it happens more to stop-n-go traffic driven cars and less with mostly highway driven cars - as I've heard heat is main enemy that stiffens rubber valve stem seals and they become rigid and non compliant? Allegedly highway cruising has better cooling and engine is not overheated as much as in city traffic - not sure if true

3. Are there any oil additives we can use with every oil change to add and protect, condition or rejuvenate valve stem seals? I've heard AT 205 - is it good?

4. I've read on German forums that there are 2 main remedies to prolong life of 50i engine - low temp thermostat (like X5M uses, I think it's around 90 degree Celsius thermostat and opens earlier and helps keep engine cooler) and the other remedy is to install downpipes to eliminate heat from cats

5. Any other advice you can share please?

Thank you very much!