1991 Sunbird corsair 19' 4.3 OMC cobra Sterndrive. I keep reading all these different answers for what type of gear lube to use in these. I've always had Mercruisers so I just use the Hi preformance 90. I read that you can also use it in these OMC's. Is this true or does OMC command a different oil? Got plenty of Merc gear oil so I'd rather not have to go buy more. Thanks guys.