The ES 250 is not a very difficult vehicle to work on (pretty much the same as a Toyota Camry V6 of the years 1987 - 1991) so your BF should be fine with the tune up (spark plugs, plug wires, air filter, fuel filter, PCV valve) & tranny flush. Are all the fluid levels ok in the car? (IE: Engine coolant, brake fluid, power steering fluid etc). The oil light might be a defective sensor, but a place like autozone or pep boys might be able to do a 'scan' for free to get a trouble code from the car's computer to tell you exactly why the light is on. B)