I just seen an owner manual from germany reccomending 5w30-20w50 for a gen2. Is this safe?

It wouldn't matter (MPG), use what you have and be happy that you still have it.

Depending on the local temps, you should be safe in using a thicker stock.

 

Australian owner's manuals are similar, show a wide range of oil weights.

The north american manuals get a little hilarious: 4th gen for example, saying to use 0W16, and if (god forbid) 0W20 is used, replace at the severe service interval, with 0W16
.

 

I used Shell Rotella 40W (straight) for my first 15000 miles with my used Gen2. And, then used Shell Rotella 15W-40W for the next 50000 miles of life with my Gen2. Shell Rotella is an oil for diesel engines primarily. I choose it because Shell Rotella has tons of detergent.

Only thing I noticed with the straight 40W and 15W-40W was that I was getting a bit of rattle from the valve cover when starting up in cold weather (say, below 35F). Best guess is that the rattle is caused by the VVT mechanism when cold.

PS I purchased my used Gen2 at about 200k miles.

PPS My oil burning and blow-by situation has improved so much since starting the Shell Rotella. So much so that I decided to see if oil burning (and blow by) improvements are still obtainable WITHOUT the Shell Rotella. Last oil and filter change I used 3.5 quarts of Walmart full synthetic Supertech 10W30. Four thousand miles since last oil change and I have consumed 1/2 quart of oil. With a substantial portion of oil consumed being captured in the after market oil water separator.

 

Maybe. More likely the missing oil is burnt?