- Joined
- Feb 6, 2010
- Location
- hopatcong, nj
i have a 1999 200hp evenrude fitch engine. what lower unite oil should be used? i used castrole full senthetic oil that was rated as gl-5 which is used in automotive applications. i have heard the marine rating is ussually gl-4. the diffrence is that the gl-5 has more sulfur in it which make some metals corrode faster like coper. was wondering if gl-5 is bad for my lower unit and should i drain it for gl-4 rated gear oil? please dont respond with a guess. i'm looking for answers from people that really know the science, an expert. thank you.