greendave, you need to look over everything one more time. First of all, "ran rough", the equipment was run rough meaning it was used hard when other people had it before me. get it? Used hard, abused, ran till the wheels fell off. Simple. All caps in the wording, started on your post first of all, Number 3, go take a look. Your post with the 2 words "WHY" and "NOT". You see any caps other than for punctuation in number 2 post, didn't think so. Ya, you may see some caps in mine later down the thread but thats expanatory. Why did I start off by saying what i use, no one said what specific model of engine it was going in, how many hours did it have, and was it a new or used model. We don't have to be engineers to put a certain oil in a machine. If it works and runs to it's full potential, then so be it.