Does oil go bad?

[58Evinrude]

We all know what happens to gas when it gets old, but what about oil? No, not when its premixed, but when its sitting in an oil injection tank. I've got oil in my VRO tank that is left over from last year, and the stuff in my sled is gonna be 2 years old before it gets used again. Does it loose anything from sitting?

Just something I've never seen discussed before.

[flabum1017]

Lemmonrude had a service bulletin years ago about oil gelling up. I'm sure there have been vast improvements since.That said, I have seen sediment build-up in tanks over the years. Not so much the oil going bad, but sediment collecting at the bottom of the tank. It would be prudent to clean the tank every few years.

[58Evinrude]

Good point. I dump my gas tank at the end of every year, and leave it empty over the winter. Maybe I should do the same with the oil tanks, burn the boat oil in the sleds, and the sled oil in the boats

[whipper]

I leave the old fuel in over the winter and drain in the spring. I use a coat hanger with a micro fiber cloth zip tied to the end and swab the bottom after wards also. Dump all the filters also. With new fuel i take it real easy for the first 10 min of running to make sure any fuel anywhere else gets run so I know Im into the good stuff before I open her up. Always run quick clean also always.

[phillnjack]

yes 2 stroke oil can go bad, but dont know exactly when.
example.
I had 2 1 gallon cans of un-opened Castrol 2 stroke oil given to me that were about 5 years old. I used 1 of the cans almost straight away and it was a bit more smokey than what I was normally getting with the same brand and type of oil.

the next of the sealed cans I kept still totally un-opened for about another 5 years, when that can got opened it was terrible, it was as if loads of water and gunk was inside it.

On another occasion I had a plastic fuel tank on a little 4 hp mercury, and one of my daughters in her wisdom thought it was the 2 stroke oil tank like on my 60hp.
she though she was being good by topping it up for me !!! I had emptied the fuel out of it and cleaned it up ready for the start of the season etc.
anyway one thing led to another and I did not use the engine for about 18 months, when I did go to it I had to get the oil out the tank.
inside the oil had congealed and there was lumps of thick sludge like stuff and what looked like bits of rust. bear in mind this was new oil from a new plastic quicksilver
container that went into a clean plastic tank.

I was talking to a friend who had similar happen in his 2 stroke oil tank and took him all day to get the tank clean.

personally now I would keep any 2 stroke oil no longer than 12 months un -opened for a boat, and drain the oil tank at end of the season when fogging a motor.
I also have a omc vro tank sitting on a shelf thats got a lot of gunk inside it.. not so sure on the history of that though. as I premix now .

maybe I have been unlucky, but I have hear a few people saying the oil can go bad or separate ?

[Krazymaan]

Just fun all of your unwanted oil products into your dodge diesel fuel tank.

[ssv1761982]

I found a can of Kendall 2 cycle oil in my garage a while ago that had to be over 30 years old. It sounded odd when I shook it so I had to pop the top to see what was up. It had jelled into a single rubbery mass and had shrunk away from the sides of the can. I know it is an extreme case but it did go bad.

[phillnjack]

I want to know why 2 stroke oil is so bloody expensive.
its getting to the point of needing to go out and steal the stuff (obviously only from the Yamaha folks).
merc premium plus for just 4 litres over here is £45 plus.. thats a joke.