Hello everyone – First post here. I have been lurking for a long time and decided to join so I can search and have some good input about my oil ideas. Here’s my deal – I own a 2000 7.3 Ford Powerstroke truck and have had it for about 8 months. First oil change was Rotella 15-40, and the truck liked it, except it was a little harder to start in the winter. I live in western WA so ‘cold’ and ‘winter’ are relative terms. I switched to Rotella 5-40 and it was much easier to start in the cold, and it again, truck liked it. I have run this oil for over 5,000 miles and intend to get an oil analysis done with this change. From what I understand, this is the farthest I should stretch my changes because of the breakdown of the anti-foaming additive which is crucial for the Powestrokes. Will the anti-foaming agent number be included in a standard blackstone? Next question is this – am I wasting my money using the 5-40 vs the 15-40? I can get 15-40 rotella for 10.50 a gallon, and the rotella synthetic is 19.00 a gallon… and I just read that I can get 3 bucks back a gallon on delvac 15-40, so it may even be cheaper to get it instead. It takes 15 qts to change the oil and with me needing to do it at 5000 mi intervals max, perhaps I really should consider going with the standard stuff and changing between 3-4000 miles? Maybe I should do the ‘winter’ change with 5-40 and the summer changes with the 15-40? This is where I am really looking for some input. What do you all think? Who has ‘strokes and has had good analysis results with what? Thanks everyone!