New here, been lurking for a while. I got into DIY with my 2002 Land Rover Discovery (111,000 miles V-8 flat tappet engine) this year and among other things have taken over the maintenance. Land Rover recommends 5W-30 oil for the truck so for years I was using whatever synthetic my shop had in stock in that weight. The truck was always a bit rough running and ticked a lot. I just figured this was the Land Rover way, the Land Rover Guy shop did not think much of it. Besides the regular maintenance I've also recently done the head gaskets and as part of that process I did an engine oil flush as I had a bit of sludge and to get rid of the coolant that dripped down there during the job. For the first flush I used 10W-40 (cheap Autozone Dino) with seafoam. One thing that struck me was that the truck ran much quieter and smoother right out of the gate with the 10W-40. After that flush I decided to give Mobile 1 15W-50 a try because of the high Zinc conc. which is good for flat tappet engines (plus was recommended on the LR forums). The oil was on sale and my plan was to see how it performed and flush it if the performance was bad or keep it until fall if it ran well. Suffice to say my truck runs really well (probably a combination of many factors) so I think I am keeping this oil in. Long story short I am contemplating my winter oil and was thinking of going with a 0W-40 or 5W-40 diesel oil with a high zinc conc. I'm not really worried about Cat damage as my whole exhaust system is aged and if it goes oh well, I'm more interested in cleaning and protecting the engine at this point. I was looking at the redline, mobile 1 or amsoil which are overkill but I figure if I only change my oil a few times a year who cares plus I have a lot of time and money put in and I really like this truck. So any suggestions on a winter oil even though it's the middle of August? I live in Buffalo, NY so our winters are cold but the Disco has an all aluminum engine and runs hot. I appreciate any advice.