I am thinking about using pennzoil full synthetic in my '89 yamaha 40 with oil injection. I've heard some people say that synthetics aren't good for oil injection pumps? Is there any truth to that? What about synthetic blends? Pennzoil says <br />its okay and some manufactures make synthetics, that make me think its alright.<br />If I switch, I am planning on running the old oil out until the low alarm sounds and then topping off with the synthetic. There will be a little mixing, is that ok?