It’s best to go with a full synthetic lower unit fluid regardless of horsepower. The smaller lower units have a small capacity and can break fluid down just as easily as the larger units. High horsepower units definitely need the sheer strength of the best synthetics. Any fluid meeting a GL5 rating should work just fine.
We have new and used parts for lower units. We do recommend new gears, seals, and bearings. But we can quote used shafts, carriers, shifters, etc.
Depending on our workload we can usually rebuild your lower unit in 2 to 4 days. Shipping time to get it here and ship it back is a bigger consideration depending on how far you are from northern Michigan.
We would consider rebuilding your own unit a medium mechanic skill level project. If you are comfortable with changing brakes on a car or truck you should be fine. Buying our high-quality parts is the first step. Included with your purchase is the bonus of being able to call or text Joe at 231-631-2263 anytime for support.
We have approximately 150 lower units rebuilt in stock. Advanced Marine also has over 400 core lower units to help us build even more.
We buy our gears from an American owned company located in Wisconsin. Last year we had the opportunity to take a tour of the factory and see the 1.2 million dollar gear cutting machine in action. The technicians running the machines were happy to talk to us about their jobs. We spend about $50,000 annually just on gear sets with this company.
Gears are not as simple as they appear to be. The 1st step to creating a quality gear set is the alloy of the metal that goes into them. The 2nd part of a gear set is the precise cut of the helical gears. The 3rd critical part is the heat treating process. We have found that gear sets that were sourced overseas do not have a reliable consistency in the quality. Therefore we choose American made gears that have remained consistent in quality over the 20 years we have been using them.
Most lower units are filled from the bottom. The one exception is a Cobra lower unit, which we will discuss later. Fill from the bottom hole until lower unit oil flows from the the top hole. Put the top screw in. Then put the bottom screw in. After initial run top off thru the upper hole.
We ship the same day you order if it’s early in the day, or the next day.
All parts and units will ship from Northern Michigan.
If you are sending your lower unit to us to be rebuilt it will typically be in the shop 2-3 days before being shipped back.
How bad is metal in the lower unit fluid or oil?
The answer is in the size of the metal. If it is fine like hair it’s probably somewhat normal and is could be coming from shifting the lower unit. When you find pieces of metal larger than a broke pencil tip, then it’s time to tear it down and figure out what is wrong. This should be done before a catastrophic failure occurs.
You should monitor your lower unit fluid and change it when it starts to turn dark. Fluid should also be changed at least once in the fall before cold weather arrives. Fluid should be changed more frequently if water is getting into it.