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.

It never good to add stuff in engines.my opinion Depends the reason your putting it in if you fix The prob Em you won't need additives,stop leak is a great thing I guess But I would never put in my car unless I was trying to make it last No money to fix.most temp fix at best my option

I don't be I've don't believe in gasthaus because gas leaves a film in gas tank What some chem do is breakdown film send it through system.back when it 1st came out I was sent to carb school.because this was Happening on wide scale.now gas pumps are pretty much safe.no lead in gas