I was reading the thread "High milage oils onther scam" and got me a thinken I run Delo 15w 40 in my 78 300 I6 with 2500miles on rebilt motor and love the oil.I'm thinking about Rotela T Synthetic 5w40 is it a good oil??????? Is the addative package the same inthe "high milage" oils as in the Delo or Rotela syn??
Do diesel rated oils have seal condtioners?
later,
Dustin

 

I put Rotella T on the same level as Delo, both are excellant oils. Diesel oils tend to have much different additive packages since the oil does more for a diesel than it does for a gas engine and it also has to handle the soot.

 

The High Mileage oils have extra viscosity-enhancing additives. This helps keep the oil thick, reducing blow-by and smoke. If you do not burn oil, you don't need this additive.

They also contain a small amount of Group IV PAO base oil. PAOs help to condition the seals. You will get the same (if any) benefit from running any syn. oil.

There may also be other seal conditioners in High Mileage oils, but if you don't have any leaks, you probably don't need them.

Diesel oils have extra detergent additives to handle the soot load in diesels. They also have extra buffering additives (usually calcium-based) to help neutralize the suphuric acids formed by the combustion of the sulphur in diesel fuel.

Diesel oils also do not have the restriction on phosphorous necessary for cat-equipped gassers, so diesel oils can contain more ZDDP anti-wear additive.

 

Rockledge pointe this thread out to for diesel oil questions. I have found it and other very informative. Can someone please elaborate on this statement. What is the restriction all about?

>Diesel oils also do not have the restriction on phosphorous necessary for cat->equipped gassers, so diesel oils can contain more ZDDP anti-wear additive.

 

Various agencies which include automotive manufacturers and the API have determined that too much phosphorus can damage cat. converters. Some diesels have something called a cat, but in reality it functions differently. Therefore, higher levels of phosphorus won't damage the emissions system in a diesel while it might a gas vehicle.

 

The "P" part of ZDDP is phosphorous. ZDDP is a high pressure anti-wear additive. It has been around since the 1930s. It works extremely well and is extremely cheap.

Phosphorous has been shown to dampen the effect of the cat converter (I have read that in time, the cat's efficiency will return). Auto manufacturers are required to warranty emmissions equipment for 5 years (I think) and this is being raised in the next couple of years to 7 or 10 years.

Sooooo, auto manufactureres have been pushing oil and gas manufacturers to remove anything that could damage the cat (because the auto manufacturers would have to pay to replace them under warranty).

As a result, the API gasser oil ratings (SH, SJ, SL and the soon to be SM) have slowly reduced the amount of "P" that can be in the oil. Reducing the P means reducing the ZDDP.

The API diesel oil ratings (CG-4, CH-4, CI-4 and the soon to be CI-4+) do not have the same limitations on "P" because the cat concerns do not exist. As a result, diesel oils can have more ZDDP, which they do because it works really good and is really cheap.

Diesel oils also have more detergent to handle the soot. The detergents are usually a calcium complex of some sort. The calcium in the detergent is also an excellent acid neutralizer (think Tums), so diesel oils have a much higher Total Base Number (TBN) than gasser oils and will neutralize acids better and longer. This is probably only really important for those who do a lot of short trips in cold weather where the engine does not heat up enough to burn off any moisture.

 

So apparently EPA forces them to replace cats out past the normal manufacturer's warranty and so the oil is engineered to favor saving the cat over added engine protection because by the time the engine shows excessive wear it would be well after the manufacturer's engine warranty runs out.

 

The oil manufacturers will tell you that the other additives are just as good.

Also, the base oils have been improving, so they will tell you that the base oils need less additives to start with.

 

I am planning on putting in Delo 400, 15-40 on my next oil change. I have a question. Do you run this in the motor all the time or every other oil change or other interval?
My truck has 120K on it.
No leakes, no smoke, I want to keep it that way.

 

I run diesel rated oil all the time, with no ill effects. I say go for it.

 

Me too I love that oil it does not leak burn anything I was using 5 30 and It still had good oil pressure and no leaks or no burning. I just can't find anything thinner than a 15w40 with delo but thier is 5w 40 rotela T synthetic I'll go to net oil change

 

There are 10w-30 dino diesel oils, but they are a little hard to find.

The 15w-40 might be a bit thick for winter months in northern states. I'm not sure that I'd run it in MN or WI, etc. in January, for example.

 

I run RotellaT in my truck.......302 100K+ miles. Kinda noisey sometimes at start up.....but runs nice and quiet when its warmed up.