Joe and Frank, thank you guys. I actually had this discussion at work with another coworker a couple months ago. GL4 I believe has less sulfur and phosphorus additives and is better suited for bronze/brass whereas GL5 is meant for differential units not using any bronze/brass components which contains more ep additives.
If it calls for GL4 85-90 gear oil, I will go with that.
I removed the lower unit and disassembled today. I’ll show some pictures, but about a pint of gear lube came out, which was relatively clean and not milky. I inspected the gear set and bearings and everything looks pretty rust free. I have a new prop seal, prop seal carrier O ring, a new prop and nose cone, thrust seal, and the o ring and neoprene seal at the shift shaft. I will also replace the shaft seal above and below the water pump and the spaghetti seal for the gear case.
The water pump impeller felt soft and pliable and fit very tight into the impeller housing. Any reason I wouldn’t be able to re use it? The case and wear the plate are pretty clean and wear free.
Thank you all again.
