MedicineMan

Recipes 

I want to pull a sample of an old ale that I have aging on oak. Is there a chance that doing so can cause oxidation?

dcp27

Recipes 

theres always a chance, but as long as you're not splashing it around, forgetting to put the lid back on, etc you should be fine

Schecter

Recipes 

Agreed, there is always a chance. Assuming you're using a wine thief (or something similar; turkey baster?) and are careful about using it properly, you'll be fine. Not sure about your methods, but I know some people add the tested sample back to the batch...I wouldn't, especially in this case.
Cheers

__________________
Primary: Hard Cider, Spiced Cider, Vanilla Cider, Cinnamon Cider, Orange American Wheat
Secondary: Empty
Bottled: European Pilsner, Liberty Cream Ale, Orange American Wheat
On deck: Bee Cave Brewery Kolsch, Cottage House Saison

MedicineMan

Recipes 

I have a 3 piece wine thief from more beer, I didn't plan on adding the sample back. I'm just worried about ruining the beer.

mike20793

Recipes 

You will be fine taking samples. The time that the beer is actually exposed to air is relatively short. It's common practice to routinely take samples to check FG readings and ensure fermentation is complete. Just don't ever add the sample back to the beer. This can cause an infection and isn't worth the relatively small amount taken in a sample. I'd say take the sample and try it afterwards. RDWHAHB. Cheers.