Hi Folks, I just changed Duramax's oil from regular ("dino") to Mobil 1 (10W 30, didn;t have delvac where I brought the truck). What do folks think of oilchange interval on the synthetics. On my gasoline engine cars, I am religious about every 3-4k. At over 10 bucks a quart for an engine with this much capacity, that gets a bit pricey.





Steve

wal-mart has moble1 in the 4 to 5 dollar range

I'm not in a position right now to do the change myself, so I need to buy it expensively from a service place. So how long do you think the mobil 1 should go? The synthetics in a gasser car certainly go a whole lot longer than 3 or 4000 miles.

I'm not in a position right now to do the change myself, so I need to buy it expensively from a service place. So how long do you think the mobil 1 should go? The synthetics in a gasser car certainly go a whole lot longer than 3 or 4000 miles.

GM recommends a 10K drain cycle. They don't differentiate between dino or synthetic.

Jim

Thanks Jim,


10 is entirely reasonable. I made the switch after about 5k partially to try to get rid of an odor in the cab (a number of replies to a post of mine and searches on prevoius posts said this might do the trick.)


Steve

Steven:

Your dealer put in the wrong oil. Mobil 1 10-30 is an automobile oil, and its API diesel rating is CF. GM specifies for the Duramax an oil with a rating of CH-4 or CI-4.

I would go back there and have them put in the right oil. A GMC dealer should know better.

Not only that, he overcharged you for the oil.

I would be cautious of when using a 30 weight oil except in winter. GM specs call for a 45 weight which equates to a High Temp Shear Viscosity > 3.7. I was using the AMSOIL 5W-30 (Shear Strength >3.5) until a heated discusson pointed this out. As a result I switched to the AMSOIL 15W-45.


I personally change my filters at 7.5K miles and perform an oil analysis. I change my oil at 14K miles. Any oil name brand oil you can buy today (including dino) should be able to go 7.5K miles, 3-4K on synthetic is a waste of money imho!

Yes, I forgot to add that the GM approved viscosities are 15w-40, with 5w-40 as an alternate.

I hate to say it, but it sounds like your dealer knows nothing about Duramax engines.

Do you folks think the mobil 1 10w 30 will do damage - I will make them change it.

I definitely would make them change it!

Don't use Mobil 1 10w-30 in your Duramax. Its gas engine oil and not intended for diesel engines. It's good oil, just not for your truck.

TC

Thanks guys for all your help. I'm really glad I checked with the experts. I brought the truck back today, and they drained the mobil 1. Unfortunately they could not get either Delvac or Mobil 1 Truck/SUV for today, and I am leaving on a trip in a couple of days. They put in the GM badge 15W40 that does have a CH-4 and CI-4 rating. Not ot excuse their trying to put over an incorrect oil on me, but there are almost no diesel pickups sold in my area (the dealer who got it for me does not for example have a diesel trained mechanic.) I needed to take it to the big GMC truck dealer in New York who sells and services almost exclusively medium duty trucks. These owners are not putting synthetic oil in their trucks. As I said, it is no excuse, but ... They claim they have 2 people trained on Duramax. We'll see.


Thanks again to all of you for your advice!


Steve

I doubt if any harm was done, but I would definitely keep records of this!


OH....PS to edit.....

I run Delvac1, all spin-on filters are changed in my Dmax at 10kEdited by: HD-Nate

Does anyone think I could have done anything to the engine driving 20 miles with the Mobil 1 10w30? I sure hope not. Again, thanks everyone for your help.

My 2002 D/A manual recomments 5K-7.5K oil changes.


All you 2003 guys are saying GM recommends 10K. The LB7's are the same are they not? Why the difference?
I use Rotella Synthetic 5w-40.


How often are you changing the Allison Spin-on? I've been changing it every 5K.


Thanks!


Go Wolfpack!


Edited by: packfan

Does anyone think I could have done anything to the engine driving 20 miles with the Mobil 1 10w30? I sure hope not. Again, thanks everyone for your help.

Steve,

Not to worry... http://www.dieselplace.com/forum/smileys/Approve.gif Driving your Duramax only 20 miles with the M1 10W30 should not hurt anything.

Thanks guys - again you really saved my butt, and more accurately my beloved truck.


Steve

Steve, you could drive 20,000 miles and it would be fine

Steve,

We are all here to help each other. Twenty miles did not hurt a thing.

Change it! It is the wrong viscosity. 15W40 means that at the engine operating temperature the oil has the viscosity of a 40 W oil. This is what GM engineered the engine for.


The oil you have in there has only the viscosity of 30 weight at engine operating temperature.


Additionally the additive package in Heavy duty diesel oil is much more robust then car oils.


Example:


Valvoline Premium Blue 15W-40 Viscosity @ 100 C is 15.0 cSt
Rotella 15W-40 viscosity @100 C is 15.7 cSt


Mobile 1 10W-30 is viscosity @ 100 C is 10.0 cStEdited by: JohnnyO

Steve,

Mobil 1 is VERY GOOD OIL. The little time it was in the engine won't hurt anything. Get a good night's sleep.

TC

Won't hurt a thing, have it on good authority you can drive 3,500 miles with diesel fuel in the crankcase.......

Thanks guys - all taken care of - Willowcreekstable, I guess that makes you one of the injector victims.... Yet another thing to think about when I'm pulling my fifth wheel.

Steve

any opinions on the Delo 400 dino? It's cheap at Costco and for the southwest, below zero temps just don't factor into starting the engine.