Rod bearings are the most discussed E60 M5 concern, with debate over whether they are an inevitable failure point requiring preventive replacement (~$2,200-$5,000) or an overblown issue when correct 10W60 oil and warm-up procedures are followed; many owners report 100k+ miles on originals.
S85 V10 rod bearing failure risk and preventive replacement
BMW E60 M5 · mechanical