New to your forum. I spent an hour searching and didn't find much AMSoil Euro or Signature information. If there's and existing thread speaking to N54s, please send me a link. 2008 BMW 335xi E92 sport with FBO (full bolt-ons) minus turbo inlets. The car makes 420 last dyno 3 months ago. My local shops are all over the board on oil recommendations. I've been using Amsoil European 5.40 but see that Amsoil Signature appears to be a better choice. N54s run hot (240 is normal operating temperature, too f*cking hot), I run a CSF Street radiator, a low-temperature oil cooler thermostat and in the summer I set MHD to track cooling which runs the fan pretty much constantly and am known to use an oil cooler thermostat delete. As a result, I maintain oil temperatures less than 210F in >100F weather. All that said, looking to make the best long term wear oil choice. I change it early and often (2-2,500 miles). Just a street racer, not tracking it.