[MC1600]

Agree with ReelMagic. I take an empty 5gal bucket and mark the outside with tape where each gal is (doesn’t have to be exact). Empty the first engine, make a note of how much came out, empty the second engine, and figure the difference (they’re obviously pretty close to the same).

Then I fill both engines from the top with the amount I removed. I always have to add a little more after restarting because of the filters (CAT doesn’t want mine prefilled).