OMC Cobra oil leaks and type of oil

[Lou C]

Hey all-I have a 1988 4.3 OMC Cobra. When I first got it I ran it on the OMC Hi Vis oil as per the OMC book with no leaks. When I winterized it last year the local OMC shop recommended I go to the OMC HPF gear oil. About a month after filling it up (winter time) a leak appeared at the relief hole in the lower unit near the water intake. In the spring I brought it to the shop, they replaced a seal in the lower and filled it with one of the newer Merc gear oils (green) saying this is the best stuff to use. Well one month later, same leak! Shop can't look at it for a couple of weeks. I am wondering if these older units will leak with the newer semi-synthetic oils, maybe I would be better off going back to Hi Vis? Thoughts?

 

[Boatin Bob]

Re: OMC Cobra oil leaks and type of oil

Lou.....I'm on Cobra #4 and #5 now and have always used the OMC Hi-Vis, the dealer I get it from charges me $38 per 120oz CDN. I have the 89 460's and each one takes 108oz, now one year I had the local shop pull the drives to lube the u-joints and check the bellows and gimbals assuming they would use OMC lube but they put in the Merc stuff (charged me $50 per drive just for the lube), I had no leaks like you but I still feel more comfortable using the HI-Vis. Now when the drives come off I insist they use HI-Vis even if I have to supply it for them.

 

[cobra 3.0]

Re: OMC Cobra oil leaks and type of oil

I use the Wallyworld gear oil in my cobra drive and don't have any leaks.

 

[Lou C]

Re: OMC Cobra oil leaks and type of oil

I think I may have figured this one out. Took a good look at the oil I saw leak out. I noticed it looked like old Hi Vis or HPF, that is brown in color, not greenish bluish like the newer Merc stuff the shop used. Looking further, there is a spot at the bottom of the water intake screen in the drive where some old oil and water had collected. When I ran it last time on the muffs I did not remove the muffs from the drive right away, so some water remained in there. When I pulled off the muffs a couple of days later, some water came out mixed in with old gear oil from the orignial leak. At least that seems like what happened, since the color of the oil that leaked out was definitely NOT the bluish green Merc stuff. <br />Maybe it is OK?