Originally Posted By: Phishin
Originally Posted By: chevytherealdeal
Can i mix rotella t4 and mobil 1 high mileage to make my own syn blend for better cold starts this winter? 94 f150 302 165000 miles. Or will the additives not blend?
They all blend. No issues. Some may not be "optimum", but no one here has EVER shown a real problem with mixing oil.
Yes I have, people just choose to ignore or discount it.
There are a (small) number of SAE papers that explore a whole bunch of engine failures that occurred in the USA as a result of changing the factory fill with the first service fill, and the residual and new oils not behaving together and causing pumpability failures at quite elevated temperatures.
They occurred...ASTM D6922 (the miscibility standard) doesn't address it...and if you are going to have problems, particularly with the OP's trying to improve cold weather performance, that's where they will occur.