Hi I have used redex in diesels & petrols & have ALWAYS found a improvment in the way the engine performs,IE in the diesels i found that the engine was smoother to drive & the pick up was improved but this was after at least two tank fulls of redex. In petrols I found the same & on my motor bike which is a jap engine with Itlian electrics the engine management system is appawing at low rev/speed ( 30 Mh ) but with redex it is vastly improved. I would use it in all my engines / have used it in the last 4 diesels & two petrols with no ill effects when used with the instructions. Bert