Sleipner bow thruster

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Senior Member
Mar 17, 2008
Vessel Name
Isle of Skye
Vessel Make
Bruckmann trawler
In Fort Loudon TN. getting an indoctrination*to College Football with the TN/Alabama game*tomorrow!
I need to top up my Sleipner which requires EP90. Went to 4 auto stores (and an hour on the web) trying to find an equivalent, without success.
What will substitute for EP 90? (GL4? Hypoid?)
90 Wt. lower unit oil for outboards?
GL-4 seems to be the*best bet; according to a Castrol note, EP90 has been replaced by GL-4.* You may well end up with an 85W-90*just a slightly extended viscosity range.

Napa shows a StaLube GL-4 85W-90.

Don't go with a GL-5, even though it's supposed to "superceed" the GL-4.* Apparently some of its*additives*may be corrosive to ***some*** metals.* You may be OK, but probably would need to check with the mfr.

BTW:* "Hypoid"*means oils compatible with helical cut (as opposed to straight cut) gears.* These require oils that can handle*higher pressures - therefore the "extreme*pressure" or EP designation.* So EP, GL-4, GL-5 are all "hypoid" oils.

Sidepower specifies GL5 for its bow thrusters.
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