I rented a 7130 CaseIH combine for wheat harvest and didn't think about it being a Tier 4 engine. Will be pushing a 35 header in short but average wheat, hopefully not alot of mud. What can I expect, need to purchase some to have on had and not sure how much to get ahead of time. Don't want a crapload left over as this is the only engine that will use the DEF on the place.