Menace

How long can you keep transmission fluid stored before it's no good? I purchased some Royal Purple fluid ... 2 years ago maybe? I never used it because I didn't know the proper procedures of changing transmission fluid, though due to recent posts I think I have a pretty good idea (still not sure if you are supposed to change it without changing the filter?) but anyway...

Going to be changing the engine oil in the next couple weeks so I thought this would be a good time to do the transmission as well, if it's still any good?

Thanks,
Kal.

Art161

Two years old should be fine, assuming you stored it at some reasonable temperature. I have seen shelf life for automatic transmission fluid stated as being from three years to forever.

It wouldn't hurt to shake the bottle to mix in any ingredients that may have settled. Then open the bottle and pour the contents into a glass container so that you can see that the ATF has not changed from the proper color and also that there are no flakes or anything like that floating around. Also check the inside of the bottle, particularly at the bottom, to see that no ingredients have settled out.

cobrakiller347

empty the container halfway into a container then shake the bottle to get the stuff that may have settled on the bottom then pour the fluid back in and proceed to shake again

Nuke

Providing it was sealed, shelf life is virtually indefinite. I might be concerned after about 10-15 years but not after 2.

Art161

As I mentioned in my previous post, some people do say the shelf life is forever. I think the problem with that is not so much the fluid, but the container. A plastic bottle can flake off a bit of its material into the fluid.

That's why you will see expiration dates on plastic bottles of distilled water. It's not the distilled water that's going bad; it's the bottle.

The one fluid that you should discard after a couple of years is brake fluid. Some air, which contains moisture, can make its way through the bottle. You don't want any water at all in brake fluid.