I asked the dealer (a kinda friendly-unformal guy) & got the esame response as i got from ma dad (a mechanic) and ma m8´s dad (another mechanic). Its cos now we´v de-restrikted we need 2 keep the pressure up in the oil tank 2 feed th engine, so the tank needs to be full. I dunno y it only hapnd wen it got wet, but it seems 2 hav fixed it.