good day to all members

i have bought E38 735 il model 2000 which has done 200,000Km
the only reason i bought it because i fell in love with my previous E38 model 98 which caused no troubles for me what so ever during the 2 i had it before i sold it ,regretfully.
with this car the story is different.the problems are first it makes noise when the engine is warm and the mechanic diagnose it as Vanos gear(never heared about it) he is calling for $5000 to fix this problem!!!!!!!
this is the first nightmare
the second nightmare was the noise the engine makes for the first 2 seconds after cold start up in the morning and when the weather is cold only, it is exactly like the noise of dry chain which goes of after oil gets up.i have called the mechanic who did the oil change (the next day after bought the car) and asked him about the oil he used .he said that he used 15w-40 or20w-50 and he is not sure about that and also it was mineral based natural oil not synthetic??wow.... so i decided to change the oil immediately though the car has done 2K with it.i have used 10w-40 and for the last two mornings i could not hear the noise again.

please i need your urgent advise about:

1- what shall i do for the vanos problem??
2- did the old thick oil caused any damage to the engine? especially to the overhead camshafts or the piston/rings and if yes what is the extent of the damage expected??

please write to me as i am really despirate for good advise
thanking you in advise
yours
Haider

I'm not a big expert on this but that non-synthetic oil is *not* supposed to be used in these cars mainly because of the tight tolerances and because they run so hot.

I'm guessing the VANOS which controls the valve timing might have gotten contaminated with the bad oil. It shouldnt cause $5000 to fix though (you could get a new engine installed for that!)

I would do frequent oil changes in the short term and put some oil cleaner in there. AutoRX is a good choice (search on google). If that doesnt work try getting the valves and Vanos cleaned and the timing adjusted.

thanks

lucas oil stabilizer cleared up my (barely audible) vanos noise. actually, it did in my old 525 (e34 m50) too.