I believe you have to use dexron/mercon for the Power steering and T4 for the tranny, not sure if you should use the T4 in your power steering or if it makes a difference. <_< The iridiums are the way to go, you probably won't notice any difference, however they'll be the last set of plugs you'll buy as they last over 100,000 miles. The Denso's have a little thinner center electrode compared to the NGK's, however you won't notice any difference. You'll be fine with the Denso's.