Charlie207
Full Access Member
I don't think swapping out a gallon of fluid will make any difference if you didn't drop the pan, clean it out, and swap the filter. Unless you do this every time you change the engine oil.For the Yukon, I exchanged 1 gal of ATF before I change all the fluid and filter.
Current trans fluid has 62K miles, 125K total. I removed the upper cooler line and used a fitting attached to a hose into a bucket.
View attachment 406509
Fluid was slightly dark but still had some red tint and smelled good.
My plan is to let the new fluid work around for a week and then change the filter along with about 3-4 gallons of fresh fluid.
Too much of a pita to drop the pan in short order, my thinking is if any cleaning is done the new filter won't get too contaminated, maybe dirty it up a bit this week with the 1 gal change.
You just made the entire system slightly more red, but left the gunk in the filter and pan to circulate.