Just picked up a one owner 93 2500, 4x4, with 200K, very well maintained - a few weeks back. I am going to be changing the fluids this weekend.
With 200K on the odometer, would I be wasting my money to run 15/40 synthetic oil in the Cummins engine? Say Red Line, Lucas or Amsoil etc. A buddy of mine said to just run 15/40 Rotilla at the 200K mark.
I am also thinking of going synthetic in the A518 4 speed trans. Any input is appreciated!

 

I switched my truck to AMSOIL at 200K and never regretted it. I ran a bypass filter and changed my oil every 20K with oil analysis at 10K. All was fine. I would have to add a quart when I changed the full flow filter and typcially one additional quart during that interval to make up for loss/leakage.

I became a dealer because I liked what I saw in using it.

Carl

 

Do it!!! You wont regret it, I personaly prefer AMSOIL. You WILL notice a difference in the smoothness and maybe 1MPG more. And great cold startup protection.

 

Carl,
Thanks for the input on the Amsoil synthetic!

Bill

 

There are two primary advantages to synthetics, whether it be in the engine, trans or anywhere else: 1) longer drain intervals and 2) better thermal stability. Personally, I don't recommended extended engine oil change intervals without additional filtration (bypass).

Synthetics are far cheaper in the long run if you do it right, using a bypass filter and long OCI. In my particular setup with a Gulf Coast-01 filter that takes 6 quarts on change, I NEVER need to actually completely dump/change the oil. I change the GC-01 and full flow filter once a year, 7 quarts to top up and I'm done.

Using Rotella-T @ about $4/qt., that's $28/yr. Do two full changes with cheap dino in the same year and the oil cost is 24qt. x say, $2 = $48. Two filters instead of one. You get the idea...

 

Does it run any cooler?

 

No, but it holds up better/longer. Heat does all sorts of nasty things to the lubricants. Synthetics can tolerate higher heat before they start to suffer breakdown, oxidation.

 

Fact or wifes tail? The P.O. put synthetic in every thing exsept the eng,said that it would cause the seal to leak!..........220,000 and no front or rear main seal seaks!
He allso changed the oil every 4,000 witch i'm trying two keep up the intervolts.
sound short, i no but I have never changed oil in a diesel, started it up,shut it down, and checked the oil, still as clean as before i porred it in!

 

Fact "and" wive's tail, so to speak. I suppose the easiest way to understand it is that synthetics leak "better" than conventional. They flow better and will show seepage or leaks in marginal seals or gaskets, where conventional oil will not.

The thing you'll see and I guess what perpetuates this "synthetics cause leaks" myth, is that in older equipment with already marginal seals, they do start leaking after replacing dino with a synthetic.

This where the Rotella-T shines. It is a GroupIII base stock that gets along well with the old seals, but has all the beneficial properties of a true synthetic.

 

All,
Thanks for everyone's input on my synthetic 15/40 post!! Looks like you all convinced me to switch to synthetic
Now, anyone know who has the best prices on Amsoil, or does it seem to hold a regular price regardless of where you purchase?

 

Ah, save your money, isn't diesel fuel something like $3 a gallon??? Dino oil changed often, put the rest in your fuel tank.

 

I wouldn't bother with synthetic. It'll go another couple hundred k on dino oil. You are far enough North that if you can't plug in in the winter, a 5W-40 synthetic would be a good idea. It'll start easier and get good oil flow sooner. Otherwise, spend the money on something else.

 

It'll go a couple hundred k further on synthetic...

 

Thanks again all for the input on my synthetic 15/40 post!

 

You'll find as many opinions on oil here as there are members. Synthetic oil lubes better and is slicker. You'll see better mileage with synthetic. In my SUV I went from 19 mpg to 21 mpg by changing to Mobil 1. I run Mobil 1 in my SUV, my truck crancase and my Getrag. Same stuff in all three places since the Diesel rated Mobil 1 is the same price at Walmart.

You engine will last longer also and be happier while it lasts.

One caveat though. When I switched to the Mobil 1 in my truck the oil pressure dropped a notch on the gauge. Probably due to the fact that it flows better. My engine has 170,000 miles on it.

Edwin