my truck gets used like the UPS truck that delivers your high performance parts. Wha tis the best weight to use for a ;ot of stop and go driving?

I personaly would recommend something like a 15/40 synthetic. Also change oil a little more often.<br>Tom

Tom's right, a 15-40 synthetic is the oil to use plus use the shorter recommended change interval.<br> I've had good success using Valvoline Premium Blue 2000 pulling the trailer. It has been replaced by a full synthetic which should be just as good.<br><br>Bill

I'd buy some of that special UPS truck oil. Its Rotella T 15w40 and change along with the filter every 5K miles. You will get tire of the truck before you wear the engine out. [laugh]

Try a quart of Lucas with your oil. Its good stuff, I use it in everything... lawnmower, racecar, weedeater, loader, chainsaw... you get the point ;)<br> Wheels

My answer would be to choose synthetic. I agree with the comment that you will likely get tired of your truck before you wear it out, with any good diesel oil, but you did say, &quot;what's the best&quot;. I don't believe you will get significantly lower wear rates with synthetic, but I do believe it will be more tolerant of hot shutdowns without coking on your turbo bearings. Synthetic is not immune to this issue, just better. So in my mind, it's the &quot;lots of stops&quot; that gives the synthetic a bit of an edge for your application. If you're on the go that much, I assume you have a real business reason for not wanting to sit very long with the engine idling at each stop before shutdown. For shorter stops, I'd leave it running, locked up, of course. Your mpg will suck but it will be better for the engine if you're only stopping for 5 to 10 minutes anyway. Just One More Opinion... :)

P.S. - I learned from earlier threads that your 12 valve engine is more tolerant of extended idling than the newer 24 valve engines, so you already have the perfect truck for what you are doing. Drive the wheels off!