Went to my local GSF store to collect, service was quick and efficient. A couple (clearly inexperienced at repairing cars) were in the queue in front of me asking for advice. They wished to buy top up oil for their ford vehicle. They had used 5w40 instead of 5w30 previously. I was particularly concerned about the advice given to them. They were correctly told that the 5w40 they had used was a bit thick but they were also told that it would ruin the engine, the whole engine might be damaged by now and the thicker oil will 'ruin the fuel injectors'. Quite how engine oil affects fuel injectors I am struggling to understand. It seemed the advisor was scaring them into buying a full oil change than the top up they asked for with totally false advice. Although the service I recieved was good I found it worrying that counter staff at GSF would dispense such false advice or lies. Either the counter staff member in question was not qualified to give that kind of advice or purposely making false claims to sell something to the unfortunate customer. Either of which i find is not acceptable customer service. I felt you should be aware.