If it were me, I'd have them do a full inspection. Anything they find could be covered by warrant and they make money no matter if your paying the bill or the warranty pays the bill. You always run the risk that they will try to upsell you something you don't need. When that happens, ask questions, have them show you the problem, don't just take thier word for it. If it still sounds fishy, defer the work and take it to an independent mechanic for a second oppinion.
As far as 2 stroke oil, I don't think it will hurt, but don't think it helps that much either. The link below is a pretty good, non-scientific study of fuel additives.
Fuel Lubricity Study
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2005 CRD "
Ol' Blue"
Red Ryder carbine-action, two hundred shot range model air rifle with a compass in the stock and this thing which tells time.
My build page- RL Komodo Rear and TJM Front Bumper, armored, lifted, JBA Steel D30, 4.10s and ARB air lockers.