the local parts place frequently runs out of stock and as a result I have used a variety of engine oils in the truck. So now I find that I have three or four partial jugs of oil, Delo, Rotella, Rotella synthetic I think. I'm wondering if, since it is due for a change this weekend, if there is a reason why I cant mix the leftovers along with whatever is available this week. I know the additive packages are slightly different but would thay work against each other? I would likely, and if possible, buy whatever I have the most of so I might end up with 6 or 8 qts of x and 2-5 qts of y and/or Z. Or should I just keep sitting on it knowing that eventually they will have each of them in the future, or add a qt to the fuel now and then?

Thanks

 

I would not mix synthetic oil with reg oil, I try to keep it all the same.

 

I've got some part jugs at home too, and I really don't want to mix them. So I just keep them at home till there's an old beater that needs topped up.

 

I personally wouldnt support a parts store that doesnt carry stock. Just order some Amsoil. Change youre oil once a year (depending on how much you drive of course) and your problems will go away.

 

So what facts do you have that keeps you from mixing oils????

 

from the oil experts it does not hurt to blend even with synthetics. on the 04.5 up trucks there is no advantage in using synthetic. the carbon loading becomes the determining factor not the additives, since the synthetic and dyno are the same the drain interval is the same. on the 04.5 up you need to use a bypass oil filter and detirmine the interval by testing.

 

Thanks guys, I understand your point Dr.Evil, we have one parts place open on the weekends or outside of my work hours, the next nearest is the same chain abotu 20 miles away and after that it's 40+ so I try to shop locally to keep from the lost time driving on my off time. I went to full synthetics on my gas motors and change the filter at 5K and full change at 10k which works out to about once a year at most. It's worked for nearly 300k on a 93 explorer and was trying to do somethign similar with the dodge, but diesel synthetic is either royal purple when they have it or rotella when they have it. Amzoil would be an option I suppose, I'll have to see if I can find a dealer halfway close.

Thanks all

 

No real conclusive facts, except I've seen enough used oil analyses that show very different outcomes with different oils used on the same engines to prove that every oil manufacturer makes their product from a different "recipe". That's enough to make me question the stability of a mixture that wasn't created in a lab deliberately. So, why take the chance when it's a simple procedure to just go buy enough oil for an oil change. We all buy these Cummins engines with the hope of having them last a billion miles, and boast about how durable they are, so I figure we better do our part in helping them achieve that.

Just my

 

Thats all well and good, until you spring a leak and have to top up somewhere else. I wouldn't just mix it all for a fresh oil change, but when I need to top up on the road, I'll use what I can get. Currently, its a 70/30 mix of Delo 400 and Valvoline Premium Blue.

 

I dont see an issue with mixing brands, but I wouldnt mix regular with synthetic. I've heard from a few knowledgeable people that it can make the oil foam up. Never seen it myself, could be a myth, but I wont take that chance

 

I'm not sure why anyone is condoning this..... Dont EVER mix oil brands, weight, type, or viscosity. Not only do not all oils come from the same cracking but all manufactures also have their own blend of additives and viscosity polymers to achieve what they want that oil to perform like, which may or may not work properly with another brand. Synthetics themselves can even be very different, which also consists of whether or not the synthetic base is petroleum or not. So when mixing oils you never end up with the same thing twice. Yes, most oils today are compatible enough that there's nothing to worry about when changing from one brand/weight to another. In saying this, if you do choose to run a cocktail of lubes in your engine then I couldn't say what could happen or even if anything would happen but I can guarantee that I would never ever treat my truck like that. Look around for a used Cummins engine and you'll see that they're in the $10k range. Bob the oil guy thread is a great place to learn about oils.