The 340 currently in my car does the same thing. About 10-15 at idle when hot. If you step on it it can get all the way back up at 50, and get about 35-40 at cruise. Around 60 when its cold. Been this way for 6 years, still runs ok. Since the day i got it, it has been ticking like its got a wiped cam or lifter, and has this same oil pressure.