calvin9853 Report post Posted March 19, 2017 I have a hydraulic system in my motor coach that calls for Dexron III. Can I use Dexron VI? I read somewhere that Dexron VI is not compatible with Viton seals. I don't know if the hydraulic system has any Viton seals but I don't want to take a chance if this is true. The hydraulic reservoir fluid runs both my power steering and my radiator fan. I want to change filters and put in four gallons to refill. The system holds 11 gallons. Can I mix 4 gallons of the Dexron VI with the Dexron III in the system, assuming it does no harm to the seals? Thank You. Share this post Link to post Share on other sites
hzjcm8 Report post Posted March 19, 2017 See my answer to this question here: https://community.fmca.com/topic/3171-retired-allison-transmission-fluids-engineer/?do=findComment&comment=78356 Share this post Link to post Share on other sites
jleamont Report post Posted March 20, 2017 Calvin, when you do go to purchase the oil make sure to read the label on the container, don't take the word of the parts guy that its compatible. There is a mentality out in the industry due to lack of training and experience that "one size fits all", don't fall for it! Share this post Link to post Share on other sites
