amsoil makes the best fuel additives in my opinion.. i have been in racing for almost 20 years and they make by far the best engine fluids.. i use amsol in my race cars (turbo buick engines) and you know how much heat they build up.. and i have never had a problem with a rotating assembly no spun bearings nothing.. their fuel additive lubes injectors and cleans them too.. great over all products.. someone else mentioned marvel mystery oil and sea foam... seafoam is the bestproduct i have ever seen as far as periodic cleaning of injectors manifolds and valve deposits.. my old 535is ran for 385000 miles while i had it and i see it around now still.. i used seafoam every 6 months and amsoil full snthetic oil its whole life..