Lower unit oil

[Bob G.]

Serial number is in my signature.

Last fall, 2022, I had a little water come out when I drained the lower unit during winterizing and the fluid was blackish color. I pressure tested the lower unit this past Spring when I replaced the impeller. I did not detect any leaks and added the High Performance SAE 90 gear lube like I have been using since I bought my boat in 2012.

June 14, 2023: Drained the lower unit fluid to change to the Extreme Performance 85W90. I allowed the lower unit to drain overnight. Filled lower unit the next day and allowed 2 ounces to drain out.

Sept 14,2023: Last day on the lake.

Sept 21, 2023: Drained the lower unit fluid during winterizing and it was tan colored, no water came out. I always let the fluid drain for 2 hours before adding new fluid. The new fluid is amber color. I have been using the yellow gaskets and used the blue gaskets this time when I filled the lower unit with the Extreme Performance 85W90. There was only 12 hours on the fluid that I drained.

First pic is the old fluid and the 2 ounces I drained out for comparison.

Old and new lower unit oil_092123.jpg

Second and third pics I took today after letting the container sit since Sept 21.

Oil lower unit oil_100223.jpg

Old lower unit oil_100223A.jpg

Plan is to pressure test the lower unit again next Spring when I replace the impeller. Not sure what to think of the old fluid in the measuring cup. The top layer is gear lube. I'm going to let it sit and see if the level of gear lube and the tan fluid changes over time. I won't be doing anything with the boat/motor until Spring except to try to keep mice and critters out of the boat.

[JOE54]

moisture somewhere leaking in

[Bob G.]

Plan is another pressure check in Spring. I remember a post by Phil about the vent/drain seals. Yellow for smooth surfaces and blue if not smooth. I put blue in this time but will replace after pressure test/impeller change. Will go with blue for next season and see how it goes.

[JOE54]

blues are good too

[SilverFox579]

Agree with Joe there's definitely water leaking in somewhere. Yep, I prefer the neoprene as they aren't "one and done" but sealing surface must be burr free.

[EuropeanAM]

Just an FYI... what you have in that container is a mixture of High Performance Lube and Extreme Performance Lube.

The two will separate when mixed, which is why it is strongly recommended they be completely drained if switching.

Suspect what you have in that lower layer is actually the "Extreme" lube with a very, very tiny bit of moisture. Put a hose on a syringe, stick it down there and suck some up to inspect it and determine if it's oil or water.

[Bob G.]

Don,

I drained the High Performance lube overnight. I added a couple ounces of Extreme Performance lube the next day with the motor raised up then lowered for 30 minutes to drain. Did this as an extra measure before filling with Extreme Performance lube with the cavitation plate level.

The fluid was all tan color when it came out. It’s been sitting and slowly separating. The top layer is the Extreme lube. I’ll get some off of the bottom to inspect. Thanks for the advice.

[Bob G.]

Used a 3mL transfer pipette to suck about 1.5mL of fluid from the bottom of the measuring cup and put some on a paper towel. The consistency of the fluid is like oil and did not flow out of the pipette like water, I had to squeeze it out. I used a UV light to check the fluid. Also did a comparison with new High Performance lube and Extreme Performance with the UV light. Going to let the measuring cup of lower unit fluid sit and see how much separates.

First pic: Pipette with bottom fluid.

Oil from bottom of measuring cup, 1,5mL.jpg

Second pic: Bottom fluid on paper towel.

Oil from bottom of measuring cup, 1.5mL_A.jpg

Third pic: Bottom fluid with UV light.

Oil from bottom of measuring cup, UV light.jpg

Fourth pic: New High Performance on the left, New Extreme Performance on the right. Took samples from new fluid in bottles.

New HP on left, EP on right.jpg

Fifth pic: Extreme Performance on right with UV light. Extreme Performance shows up with a UV light. Might make it tough to differentiate Extreme Performance oil from DFI oil as they as similar in color. The new fluid and fluid from the bottom of the measuring cup appear to glow the same with a UV light.

EP on right with UV light.jpg

Sixth pic: High Performance on the left with UV light. Does not glow with the UV light like the Extreme Performance oil.

HP on left with UV light.jpg

[EuropeanAM]

Interesting... only thing I can say for sure is there IS some moisture in the lower portion (perhaps more than just a couple drops).