Merc alloy screws / bolts

[john493]

Any ideas why MB insist on using single use aluminium screws on their engines ? Never known any other manufacturer do this for engine casings.
eg - on my C350 with the M276 engine, the top front cam-chain cover M6 screws (with blue dots) are alloy single use. Any reason why I can't
change them to stainless screws rather than buying a new set from MB ?
Same for the transmission pan, M6x40 alloy screws, single use.

TIA
John

[trevalvole]

With aluminium being more reactive than stainless steel, when the two are in contact the aluminium can corrode.

https://en.wikipedia.org/wiki/Galvanic_corrosion