I have a 1967 Volvo 122s, Should I add additives to the engine? Why or What? Thanks!
You might want to add a lead substitute at each fuel fill-up. Many older model cars, such as pre-1971 GMs, were not designed to run on unleaded gas. The valves in these engines needed lead to lubricate & cushion the valves as they open & close. Otherwise they will recede & stop sealing properly when closed causing lost compression that can only be fixed by doing a valve job. It is possible now to have new hardened valves & seats installed when doing a valve job. HTH. -Jim
I would also stick with non-ethanol gasoline. The ethanol can sometimes affect the rubber diaphragm in the fuel pump causing premature failure. Your car probably has a B-18 or B-20 engine, and probably a pair of side-draft S.U. Carburetors...they really arent affected by gasohol...
You might also watch out for detergent oil. That can loosen sludge that is already stuck in place in the engine allowing it to float in the oil and land somewhere it shouldn't.