My 16 year old grandson recently bought a '79 Spider with SPICA fuel injection. We changed the oil the day we took it off the trailer. The car seemed to be running rich but had good oil pressure. We put about 300 miles on it and changed the oil again. After about 50 miles I noticed less oil pressure. At about 75 miles the car shut off at a stop signal. I checked the oil and found it contained gas. I drove it about 2 miles to a garage. The oil in the crankcase contained so much gas it was flammable. The mechanic says it cannot be the fuel pump because it delivers gas at too low a pressure to cause the problem. There is no indication that the head is cracked and no oil leaks. Are there any repair manuals that might address how gas would get into the oil? Any suggestions?