My daughter has just bought an 8yr old car with average mileage from a dealer that sells that brand, upon checking the dipstick after 2 weeks of ownership it was empty, no oil showing. Garage says it's the strainer, a common problem we'll fix it & modify it. They say there's enough oil in the engine that it wouldn't of caused any problems. They won't do any stripping down of the engine to check. There is a 12month warrenty with it & now it's "fixed" they want a 600 mile test to see if any oil disappears. If it has done any other damage how long will it be before it shows?