Changing the gear oil on my 1990 4.3/alpha one.. the oil that cane out had a small amount of milky streaking in it, i know not good. I spaced getting new plug seals. The old ones look fine although they're hard. Can i just use a regular rubber o-ring instead? Im going to drain the oil again after taking it out tomorrow and see of its milky again. (This is a new to me boat) thanks!