I have been in the US for over eight years. I have retained my lack of accent and continue to use English idioms and pronunciations; very few Americanisms have crept into speech. There is one linguistic tic that I picked up early and oddly marks me out as non-local almost as much as my lack of accent.
When I talk about a freeway I say “I drove on The Five”. The addition of the definite article to the freeway number is Southern Californian habit that is not used up in the Northern half of the state. A local would say “I drove on Five”, or possibly “I drove on i-Five”. A former colleague, unaware that I had arrived in The Bay Area from Los Angeles, expressed surprise at my use of the definite freeway article. Once I explained the six months spent living close to The Ten, she understood