When I had my initial 50 hour service done on my b2620, the dealer mechanic said they recommend changing the engine oil and filter every 100 hrs and the other filters as well. The manual says my next engine oil and filter, HST filter change is at 200 hrs. Then at 400 hrs it gets everything including hydraulic oil and filter. Who is right? I know dealers make their money on service and parts but I do want to keep the thing well maintained.