Old fork oil - different colours?
 

I changed my fork oil at the weekend and was a bit surprised when the old contents of each fork were completely different colours - one fork's oil was a sludgy grey liquidised brain kind of colour whilst the other's was a sludgy reddish brown evil curry sauce sort of colour. They also both (mostly) stayed separate from one another in the oil tray I poured them into.

Googling suggests this is not an entirely uncommon finding but I couldn't find much to explain why. The main theory I saw is that the factory put different types of oil in each fork (possibly even different grades). This would seem to be an obvious answer but it sounds a tad unlikely to me. Anyone know the answer?

Re: Old fork oil - different colours?
 

Maybe it had a leaking fork seal at some point in the past and only the affected fork leg was dealt with. So could maybe be original oil in one leg and newer stuff in the other.

Re: Old fork oil - different colours?
 

Can't say with absolute 100% certainty but I am 99% sure this is the first time the forks have been off the bike since new. Bike was just over a year old when I bought it with 3k on the clock so wouldn't have thought it would have had any fork work done in that time.

Re: Old fork oil - different colours?
 

rust...

Re: Old fork oil - different colours?
 

Water contamination changes fork oil into weird colours and smells.

Re: Old fork oil - different colours?
 

I wondered about that. And rust. Although the spring etc all looked to be ok with no obvious signs of corrosion. I confess to not really knowing what lurks at the bottom of the forks!

Anyway, here's a piccy of my multi-coloured gloop, for your viewing pleasure...

Attachment 13807

Re: Old fork oil - different colours?
 

... and think of the amount of bikes where no one has changed the oil!

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Old fork oil - different colours?
 

As disgusting as that is from a functional point of view, it is actually quite pleasant to look at. Like one of those sand landscapes you get down the beach.

Maybe you can sell it was a bit of modern art?

Re: Old fork oil - different colours?
 

That block paving could do with a clean... [/derail]

Re: Old fork oil - different colours?
 

Yeah that's normal, like sid says water and oxidation of the oil from seal leaks.

Reason you don't get rust inside is oil is designed to stop it. Emulsifier additives etc.