i know that some grease's are not compatible so with a used motor that i do not know any history how do i know the proper grease to use ? any marine grade grease ok ? these are for the grease fittings on my merc what i just bought was some "sta-lube " marine grease in a tube for a grease gun . i can see two color of greases on my engine now white lithium ? some dark grease who knows what it is. so there a good chance that the grease i just bought will be compatible ? the sta-lube is a light blue do i just keep pumping till the old grease keeps coming out till it turns blue ?