i have a 2018 ram 3500 with the 6.4 hemi i been running it on 91 octane with no ethenal but its expensive at 3.54 a gallon. thinking about going to lower grade but here in minnesota we have 87, 88, 91 and 91 has no ethenal. 87 has 10% and 88 has 15% ethenal. and i think our trucks run on 89...