I have 1/3rd. ownership in an Iron&Oak; 22-T splitter. (and yes, I only use it vertically, the CORRECT way). They issued a re-call on the ram, so I contacted them, and the new replacement was here in about 4 days. Great cust. service. We swapped it out tonight. Now it had hydraulic fluid in it, but they reccomend ATF dex III if splitting below 30 °F , which we do. I know we didn't get all of the old fluid out, so should we be concerned or not worry? I don't know about the compatibility of the two fluids. Thanks, JB