Lucas fuel treatment for volvo?

Check your radiator, S60's had corrosion probs as I recall. check your airfilter and intake system-make sure nothing is blocked up or leaking. Ditto any crankcase breather system-the 240's had trouble there. New plugs and leads won't hurt, and fuel filters. Check fuel pressure with a gauge, check fuel regulator. WARNING: Old fuel hoses may leak if disturbed and not replaced. Check blowby, and compression. it's a lot more than a can of oil, but it's due, so do it properly if you're going to keep it. Check & clean/replace injectors. Check fuel pumps and their relay(s).