I have an 03 Suburban I recently purchased. I'd like to change the trans fluid and put in Dex 6 (Dexron VI) The fluid in there now is redish/brownish color. 155k miles. Walmart seems to have discontinued their Supertech Decron VI. So I'm not finding a cheap Dex 6. So should I exchange with Dex 3, as sort of a rinse (pulling pan, replacing filter, removing return line method,,, dive for a week on fresh dex 3 then pull return line and switch to Dex 6? or just use the afore mentioned method and go straight to DeX 6. Got it stuck in my head I should have a rinse cycle in there, but don't want to pay DeX 6 prices for the rinse. Thoughts on a rinse cycle? Transmission works fine, no issues. The 5.3l has had lots of work done (PO was determined to get a small leak fixed, so it has receipts from local shop with new oil pan and gasket, new front & rear main seals, knock sensor, intake gasket, new TB assy, and more! Thanks for helping me overcome some minor OCD and alleviating the "Wrapped around the axle" phenomenon. C.