all you can do is find any aluminium parts you wanna polish, remove them from the engine, and rub and rub and rub and rub and rub and rub some more with wet and dry paper. . . start with harsh paper (120 grit) then work your way through 240 then 400 then 600 then 800 then 1200 grit papers to remove the scratches. . . .after that use some "autosol" (from halfords) to bring up the shine !!!!!!!! then your aluminium bits should look like this> p.s it'll take ages . .about3 times longer than you want it to