1989mach1

I change my gear lube at the beginning of every season so any moisture in it from sitting over the winter is talkin care of. It gets a full drain drives and bottle every 15 hours 20 max.

92nsx

That is VERY true with EP solution (ep 2500) that we use. The only time when it got changed out is when that room started on fire, other then that we just maintain the correct level

zgoo

You are right, thing happen in the lube from water, shear loads and metal. It seems a lot of us leave the oil in the drive from 25 to 50 hours. Would you not agree that the oil is at its worst in the last 1/3 of its life? Yes, so we don't want to throw good oil out with bad right?? You can all agree that if you change your oil in the drive every 5 hours it is much better then 25 or 50 hours? But we do it that way right? So if you keep your drive oil at its best, your drive will last much longer. But changing all the oil every 5 hours would be wasteful, so by removing some slightly used oil and replacing with fresh oil does what, improves the quality of the existing oil in the drive by 17%. Sure at the end of the season drain all the oil and start fresh would be a safe bet. To change out 1/2 of a quart is cheep and easy because no pump is needed. Look at the cost of our out drives, why not try something that the oil companies would never tell you to do it, they can't sell you more oil. They do this on big turbine units which take a butt load of oil and they don't have to shut them down as this can be done while still running.

cgpsu309

There may be some merit behind the theory, but I don't know if I want to do that just about every weekend.

jayboat

iTrader: (1)

Nice to see this concept being discussed here.
Something I've been interested in for a while and think it could be adapted in any number of ways to suit a particular situation.

cig92

I would be changing the oil in your drives at the end of every season with fresh fluids. if you don't change it until spring, you may be leaving condensation in your drive to work at pitting your gears all winter, same goes for your motor oil.

zgoo

You could always drain 1 quart and add 1 quart ever 10 hours which would still be much better then using oil with 20 to 30 hours of use. I have been doing this with all my diesel trucks. Every 2,000 miles I suck out 2 quarts and add 2 quarts. Diesel oil starts clean and slowly becomes jet black from a build up of carbon black which is super fine black carbon. The carbon black is about 5 microns in size and engine oil filters allow about 50 microns to pass through, so the longer you run the engine oil, the blacker and blacker it will get from the carbon black build up. So by doing the fast oil drain and fill the carbon black never builds up to a high level. There is a a device called a bypass oil filter which is a 3 micron filter that takes a small amount of oil and filters it through the 3 micron filter and it will come out as clean as new. But the flow is so slow because of the fine filter you could not use the 3 micron by itself as the flow rate is less then the needs of the filter. If you put one on a diesel engine the oil will remain just like new!!! So the problem with out drives is there is no filtering of the oil, the longer you run it the dirtier the oil becomes and the more wear on the gears and bearings. The reason I share this with you is not because I'm cheap but more worried about doing the best for the drive.

SB

iTrader: (1)

If you have a stock or mild small block with an Alpha don't worry about it.

If you have a Bravo with a stock or mild 502 or bigger, well, then, you should be worried.

BUP

iTrader: (9)

CIG92 is correct in post 16. Plus you want all the corrosion inhibitors that are added in the oils intact & new while the boat is stored for x amount of time. Used oil has some if not a lot of the oil additives depleted plus the oil is oxidized.

All the marine OEM's recommend stored boats for periods of time have the oil's and filters changed to new for the lay up

zgoo

I guess, my opening title was a little off by saying never change the drive oil, but never change it the OLD WAY. It dosen't matter how high a HP motor is behind it. It has to do with keeping the oil at it's peak, since we can't filter the oil but just wait for it to get nasty the last half of it's life and that nasty oil is protecting how much $$$$ in the drive?? So new oil in the top working its way to the bottom where some of the worst oil in the bottom is removed, pretty simple! I know a few old machinist guys that I have bought their old metal lathes that have closed non filtered gear boxes on them much like a out drive. They did the same thing I'm telling you guys and I open all the covers on the machines I buy and do an inspection on the gears and I'm always amazed at the condtion of the gear boxes, they still look like brand new, with no metal oil colored staining on the inside, gears and bearing look new and these machine are about 30 to 50 years old. All because they never let the oil get to the dirty stage.