Anyone ever... SM465 Question...

[Shiprekd]

Something that might help, is that obviously, marine gear drives have to be completely sealed as they're submerged in water (especially seawater). Not like our diffs, t-cases or even tranny's.

The oil has to keep from foaming and expanding too much or else it'll blow the rubber seals. It also has to keep the water away from the components.

I've seen a bunch of times someone will bring in their boat where they did an oil change on the cheap using automotive grade and blown seals out. Water gets in and makes a thick vanilla milkshake of the insides. The water stays in suspension and rusts the gears.

A pair of outdrive gears alone can cost anywhere from $300-$700 and that's not including the $80hr marine mechanic

 

[Chevy305]

I think that marine gear oil is what I should be using in my diffs. I constantly get water or mud in them and its a pain in the ass.

 

[k204dr]

I run 50 wt in mine. the EP stuff is for diffs only. it will actually attack the syncros in the trans. my scout also runs 50wt, and shifts alot better than when it had 80/90 in it. theres a big writeup on this, but I don't recall where I saw it. but it will run with most any of those in it, they're pretty tough trans.

 

[K5MONSTERCHEV]

You guys are nuts that stuffs too thick. MTF or 30W.

 

[Shiprekd]

the EP stuff is for diffs only. it will actually attack the syncros in the trans.

Not looking to hijack the thread . Just want to make facts known and any misconceptions concerning some marine grade lubricants. Like Mercruiser, Mobil, and Amsoil. I've been working on boats for close to 30 yrs..

"It maintains extreme pressure protection even when contaminated with as much as 10% water. It promotes longer seal life, preventing excessive water leakage. Marine Gear Lube protects against rust and is compatible with aluminum, copper and brass alloys."

I'm not even going into the benefits of Marine grease. Ever open a container of wheel bearing grease and its cloudy??? That's simple moisture being suspended in it.. I have yet to see a rusty spindle with a hub packed full of marine grease.

 

[79Beast]

GM calls for 90W in 465's. If it's really cold, you can run something thicker. However, I'd rather go thicker than thinner in and old 465. 75 or 85/140 would be fine as well. I really think 50W would be too thin.

 

[Confedneck79K30]

why would they say to use 90w if it had a 208 behind it?

 

[Chevy305]

GM calls for 90W in 465's. If it's really cold, you can run something thicker. However, I'd rather go thicker than thinner in and old 465. 75 or 85/140 would be fine as well. I really think 50W would be too thin.

Why would you run the thickest weight gear lube if its cold? Wouldn't it make it HARDER to run with the thick gear oil?

 

[Uncle Fester]

I'm running 80/90 in mine with BG Products Multi Gear Concentrate (MGC) added. got that in the front and rear diffs, plus in my SM465 and NP205.

 

[diesel4me]

thicker is worse...

Why would you run the thickest weight gear lube if its cold? Wouldn't it make it HARDER to run with the thick gear oil?

Yes,the thicker the viscosity,the harder it'll be to shift it in cold weather..at least that was my experience when I used thick stuff like 140W or added a thick additive like STP or Lucas...plus my truck wanted to move forward in neutral on frigid mornings,like it had fluid drive!..


I guess you could use a multitude of different products,from Dextron to motor oil,to EP gear oil,Marine rated whatever,and still not harm the tranny..but I'd stick with what GM says to use in it myself..go thinner if cold weather shifting is the trouble,or use synthetic..it cured my hard shifting woes..but remember,if its a synchro going out,no amount of whatever lube you put in will fix it..

 

[DEMON44]

whats with the big debate You can run goat piss in a 465 and it'll be fine.

 

[darryl]

yea quaker state also has the gm synchromesh fluid and you can also get the mopar stuff from dodge i have used synthetic 5/30 with great success in a work truck many times in the 1970's 50w was used in sm465 and old spicer 5spds in 2 and 3 ton p&d trucks and never caused a problem gearlubes would cause severe sludge buildup due to never having decent or any oil changes
80/90 gearlube whether synthetic or dino has the same flow rates thru a viscosimeter as 30w engine oil at room temperature in other words they are the same thickness but are in different use catagories so the numbers are pretty much useless to be able to say 80/90 is thicker or heavier than 50w
hydraulic fluids pose the same type of numbering comparison problems
baiscally wht it comes down to is a sm465 will be happy with synthetic or dino 80/90gearlube 50w engine oil 30w engine in severe cold below -20c
75/140 full synthetic gearlub any weather 10/30 synthetic as a daily driver
15/40 synthetic offroad use and a good synthetic atf if you can stand the gear rollover noise and want very easy shifting