The R is a desert racing machine and is water cooled, has won the Baja 1000 several times... The L is the dual purpose version and is air cooled. The service interval on the R is depending on how hard you ride it. I change oil and oil filter every 1500km, +- R250. But I know of guys who change every 6000km, so it depends. I feel more comfortable with changing more often, doesn't cost a lot of money,... so why not? Only other thing to service is the air filter, I clean and lube after every ride (maybe every second ride, depending on the conditions)