Hi, I bought my van with 24k miles .I always changed oil myself, using Mobile1 5w30 syn.at approx80K started to misfire .confirmed by my mechanic to be cyl #4. I read on your repair topics / engine misfire page.

d. wrong weight motor oil was installed holding the cam followers from adjusting.

oops I'm supposed to use 5w20, my bad. I need your help! what do I do? I have disassembled rebuilt engines before so if you could please tell me what to do