"Justin:
The choise is all Yo
"Justin:
The choise is all Yours. My comment was mainly for Chris and his 'warning' post. I in fact I worked for Volvo Penta, Sweden back in late 70's early 80 at their sea trial station (R&D), resposible for prototype installatons and testing. I ran the duo props years before they were even known to be comming, and we did quite a lot of oil testing, not to forget drive dismantling! In Your combination Aq125, lubrication wise You may run whatever You want except water! Even cooking oil may do! The upper units we 'loaded' with GM350's giving 450Hp at 5500RPM without big problems when using the right oil.
There are two problems that may occur in the upper unit.
One is the conuses gets polished. The first inication is 'smooth' shifting normally followed by hard to get out of gear. If You need to get it out of gear by pushing the gear cable, it may easily lead to cable failure!
The second problem is the play of the primary shaft. It starts with encreasing shifting 'bang' forward or reverse depending of propeller rotation. It is caused by wear of a brass ring under the lower gear holding the shaft. As it gets thinner, the play encreases and the slide hammer effect may be so hard that the ring breakes and the shaft pops straight through the top cover! Unfortunatly too many people (mechs?) correct the encreased play by changing the upper shim nut to a thicker one to get the right play. It works 'ok', shift bang gets reduced until the shaft comes up! However theese cases mainly happends on the big V8 and diesels, so just relax!!! Hoewever I thought it perhaps might be nice to know!
Enjoy Your boating, but please do not take my cooking oil comment to literaly!"