Terry Stafford

Bought my first diesel 2003 dodge 2500 crew cab long bed 2 wheel drive, has 280000 miles on it! Should I stay with a conventional oil or go to a synthetic oil! And how many ouarts of oil does a 5.9L hold? Thanks for the help!

ftltmp

I am partial to Amsoil Syn 15w-40, its all I have ever used since day one. Mine holds 12qrts.

CRF450R RIDER

do you see any engines or parts lasting longer from using synthetic? i personally have not, so i dont spend the extra money on synthetic when there are engines out there lasting just as long on non synthetic as synthetic.

ftltmp

Price wise it's not that much difference for me that would make or break the deal. I guess it's personal preference.

CRF450R RIDER

.boB

There are two reasons for using synthetic oils:

1. High heat. By that I mean temps well above 200* for extended periods of time. Not really that big of a deal in a truck. Oil is heated mostly by rpm's, like 6,000 rpm's lap after lap.

2. Extended drain interval. Based on UOA, my truck can run conventional oil for about 15,000 miles. I change the oil every spring. If you plan on driving more than that in a year, it might be more convenient for you to switch over.

The Cummins uses 12 qts. 3 big jugs. I wait for Valvoline Blue to go on sale at Wally World.

As a side note, there are only 5 true synthetic oils on the market, and none of them are diesel oils.

soulezoo

I am interested to see the link that backs the claim of your "side note" below and the criteria used to make that statement.

.boB

How do you prove a negative?

A true synthetic oil is just that, a synthetic. It's a man made product. A true synthetic start with a man made PAO base stock, and adds their particular additive package.

A semi-synthetic starts with dino oil, and refines it to a point that it (reportedly) performs well enough to be called a "synthetic", even when it's not. And then they add their particular additive package. When push comes to shove, a UOA will prove that they don't perform as well as a true synthetic.

That's not to say that a semi-synthetic is a bad oil. In most cases it's just fine . But it's not a synthetic. If you're paying synthetic prices and expecting synthetic performance, you're getting ripped off.

Do your own research. Find out which oils start with a PAO base stock. Start with your favorite synthetic oil that's in your truck right now.

CRF450R RIDER

I also have read that there are only a handful of true synthetics. Never researched it, but I've seen that statement more then once.

soulezoo

I have researched. Quite a bit in fact. To say there exists no true synthetics (based on the correct PAO base stock info below) that are made for diesel is just plain false.

Here's a link to a TDS (technical data sheet) of just one.

http://www.schaefferoil.com/documents/244-9000-td.pdf

Royal Purple is another that makes a full syn Diesel oil...

Redline is yet another...

I really have no interest in what others run- their choice.

But I don't like seeing misinformation being spread.

ofelas

I see a few different diesel oils by Amsoil labeled as 100% synthetic as well.
HDD 5W30
AMO 10W40
AME 15W40
ACD 10W30

I believe they have a couple "Euro" synthetic diesel oils as well.

.boB

I stand corrected. I went back through their web sites, and found some diesel rated true synthetic oils. I don't remember finding them when I was looking a few years ago.

I also went looking for any indications that other oils are a true synthetic. I couldn't find any. Some of them appear to have some PAO base stocks mixed in with the dino base stock. But no clue as to how much.

CRF450R RIDER

If you read what i wrote, i said I NEVER RESEARCHED IT. i had read a that there are a handful of true synthetics. To add into that statement, i also read that they are not for diesel. Sorry for this "misinformation" that i never claimed was true.

6.7L MegaCab

Terry,

Unless you know the history of your truck and know that the oil was consistently changed, assuming conventional oil was used, I would venture to say to stick with conventional oil. I am a firm believer in synthetic oil, but because of the detergents and other chemicals used to make synthetic oil, if the conventional oil wasn't changed at regular intervals and allowed to sit, it has the potential to dry the seals and leave a wax like residue (that keeps it from leaking). Synthetic oils will naturally strip away that residue leaving the potential to cause a leak, that would then be blamed on the synthetic oil, when it was actually due to poor maintenence and using conventional oil.

Now saying that, these engines are built to last, even if you did run synthetic, there is a good chance there wouldn't be any leaks, and if there were, I would think it would be just the oil pan. If I bought a high mileage truck such as your's, first thing I would do is run engine flush and put in synthetic oil, expecting to do some maintenance afterwards at the next oil change.

I good friend of mine bought a 98 12 valve a few years ago; he's ran AMSOIL Heavy Duty Diesel and Marine Synthetic Oil since shortly after he bought it and just had to change the seal on the oil pan....although now that I think about it he may have changed it before he started running the oil...been a few years since I had to think about that.

Hopefully this helps somewhat.