Mixing different weight oil. Same brand.

[JDietz]

The truck. A stock 04. 5, with only has 22,500k and has had Amsoil 5w30 Diesel oil since August last year, with about 7k on the oil, so I change oil once a year. With the 5w30 oil, my oil pressure is actually slightly more then it was with 15w40 dino, but I'm just a little leary using that light of oil pulling my 34' Airstream, although on my last trip from Georgia to Colorado and back, I got between 12 and 14 mpg pulling the 8500lb trailer, and my best mileage has been 21. 8 not pulling. It does not use oil. My question is what happens if I put in 6 qts Amsoil 5w30 and 6 qts of Amsoil 15w40?









STOCK 2004. 5 Black Quad cab Larimie LWB NV5600

 

[tron1959]

I can't answer your question. I have a question. Why would you want to do that?



I would use, I do use a regular 15W40 oil. For the amount of miles you put on your truck you are wasting your money by using synthetic. My opinion of course. Follow your owners manual. Probably for your climate a good name brand 15W40 oil will outperform your needs. Spend the money you save on some good wax and protect the outside so it will last as long as the engine.

 

[jelag]

I would never very from the oil recommenditions in your owners manual... . Cummins has worked hard with their engineers to develop an oil that functions well under all conditions... . I can't understand why you'd make a chance that could effect your engine warranty.....



Yes your oil pressure will be lower with the lighter oils over the 15W40, as the 40 weight oil has a higher viscosity, which in simple terms means that its thicker... . and takes more pressure when its hot to push it out the leaks... . the calibrated leaks that make an oil system work... .

 

[NJones]

You will end up with a 10W 35. No big deal. Do it if you want to. I've done it several times over the years with diesels to get the weight I wanted or just had 2 different wts oil. These are not finicky light built engines that will fall apart at the slightest variance from recommedations. I'm nearly 50, and have had a bunch of motorcycles, cars, trucks, boats, heavy equipment, tractors , Dad had over Road Tractors and I HAVE NEVER HAD A FAILURE OF ENGINE from oil. I would bet you haven't either. Even the cheapest oils that are diesel rated will do a fantastic job. Mix it and drive down the road with confidence -- I would- --and have.

 

[betterthanstock]

With the 5w30 oil, my oil pressure is actually slightly more then it was with 15w40 dino,

No, it isn't. It has been discussed on here many times. The oil gauge is fake. It's just a switch at 6 psi. The needle moves according to what a real gage would move. When cold, it's higher, when hot, it drops at idle, then picks up as you rev it up. Fake computer simulation. Just like most, if not all newer vehicles. It cuts down on customer complaints, and it makes it look like you have a full set of guages, while saving a few bucks on a real pressure sensor.

 

[JoelMartin]

No, it isn't. It has been discussed on here many times. The oil gauge is fake. It's just a switch at 6 psi. The needle moves according to what a real gage would move. When cold, it's higher, when hot, it drops at idle, then picks up as you rev it up. Fake computer simulation. Just like most, if not all newer vehicles. It cuts down on customer complaints, and it makes it look like you have a full set of guages, while saving a few bucks on a real pressure sensor.

That is pretty interesting; I never heard of that before.

 

[Pawpaw]

That is pretty interesting; I never heard of that before.

The definitive thread on the subject:



https://www.turbodieselregister.com...311-settled-your-oil-pressure-gauge-fake.html



Bob

 

[Money Maker]

It is true. I just replaced my switch, I had read about it here long time ago as well.