Hello we have an E53 with a m54 engine. The engine was recently rebuild because there was a problem with the block as cylinder 2 sleeve had movement, so we took it back to the machine shop to get it rectified. for the first start up we used regular castrol 10w-40 oil and noticed it had a noise like lifter ticks and the vehicle would hard start on cold but ran okay however as there was a slight misfiring that could be felt and the car threw different codes. Afterwards, we changed the oil to synthetic 5w-30 and the lifer tick noise went away but when the engine got hot, cylinder 2 started to misfire as the code suggested. we did a compression on cylinder 2 when cold it is 160psi and when hot it is 90psi. do you think the oil change affected the car or what would you suggest?
Well if you ask me they just did a crappy job rebuilding it. I see that all the time guys say they ought to rebuild stuff but they don't all their ass from their elbow. If I were you I would have an independent mechanic. Check it out to see if the engine wasn't rebuilt correctly and if it wasn't I go back to the original guy and probably just demand my money back because if they can't rebuild it right having them do it a second time would probably be even a worse job because they wouldn't get paid the second time
