last week i picked up a 94 RS as a daily. i did the oil change using the using conventional valvoline, later i found a jug of Quaker state syntec hidden in the trunk. so it looks like the previous owner was using synthetic.

my question is could there be any harm that could have come from unknowingly using the wrong oil for about a week (roughly 250 miles most of it highway cruising to work)

the b18b is not the original. from what it looks like it out of a 99

TIA

 

you can switch back and forth between conventional and synthetic no problem. Its just a myth that once you go synth you cant go back. hope this helps.